bio final

Species are a group of organisms because different species may have different criteria for determining whether they are from the same species or just two different species that may have similar characteristics. Generally, a species is a group of organisms that can interbreed and produce fertile offspring, but there are certain exceptions.

FOUR SPECIES CONCEPTS Biological Species concept This concept is used by taxonomists Those species that can interbreed and produce viable offspring Can be used to define diploid, sexually reproducing organisms It relies on reproductive isolation - when 2 populations cannot interbreed, they are not from the same species States that no gene flow occurs between two populations if reproductive isolation occurs because they cannot reproduce together It uses multiple lines of evidence. There are two types of reproductive isolation Pre zygotic Temporal Habitat Behavioral Gametic behavior Mechanical Post zygotic Hybrid viability Hybrid sterility Disadvantages Can't be found in fossils Difficult to apply - geographic barriers Determining the boundaries of a species can be difficult, as genetic and morphological data can vary within and between populations. Lack of consensus: There is often a lack of consensus among researchers on the appropriate criteria for defining a species, which can lead to inconsistencies in species designations. Can be subjective: The interpretation of genetic and morphological data can be subjective, leading to different conclusions about species boundaries. May not reflect ecological or functional differences: The phylogenetic species concept does not necessarily reflect ecological or functional differences between groups of organisms, which can be important in some contexts.

2. Morphospecies Concept The morphological species concept defines a species based on physical characteristics such as anatomical features, size, shape, coloration, and other observable traits Morphological differences between individuals of the same/different species Fossil identification Helpful with extinct/extant species Can be applied to extinct AND living organisms Helpful when genetic data is unavailable Disadvantages Cannot identify cryptic species Limit of variation between populations - characteristics can vary within populations, making it difficult to determine if individuals belong to the same or different species. the physical features used to distinguish between species can also overlap, leading to ambiguity in species identification. May not reflect genetic differences

3. Ecological species concept Organisms that have the same resources, environmental tolerances and face the same predators Identifies species based on their role in the environment Ecological niche, behaviour, and interactions with other species Can be used to identify bacterial, archaea, or organisms that reproduce asexually Reflects ecological interactions Useful for conservation research and efforts Can reveal cryptic species Disadvantages Not useful if one does now know anything about the role of the organism Difficult to apply - ecological interactions can be hard be complex Ecological differences may not reflect genetic differences and differences species can occupy similar ecological niches Limited to organisms - cant apply to bacteria and viruses as they do not have well defined ecological niches May not reflect historical relationships

4. Phylogenetic species concept Evolutionary history of populations based on the DARWIN - stated that all species are related by common ancestry All species form a MONOPHYLETIC group, or clade They are identified by synapomorphies at genetic, mental or structural levels According to this concept, species are a group of organisms that are bound by ancestors based on their morphological and genetic traits and lineage Widely applicable Reflects evolutionary history Can be applied to all organisms Disadvantages Can be difficult to apply - incomplete data on lineages, etc Limited data May not reflect functional differences

This concept is used by taxonomists Those species that can interbreed and produce viable offspring Can be used to define diploid, sexually reproducing organisms It relies on reproductive isolation - when 2 populations cannot interbreed, they are not from the same species States that no gene flow occurs between two populations if reproductive isolation occurs because they cannot reproduce together It uses multiple lines of evidence.

Pre zygotic Temporal Habitat Behavioral Gametic behavior Mechanical

Post zygotic Hybrid viability Hybrid sterility

Can't be found in fossils Difficult to apply - geographic barriers Determining the boundaries of a species can be difficult, as genetic and morphological data can vary within and between populations. Lack of consensus: There is often a lack of consensus among researchers on the appropriate criteria for defining a species, which can lead to inconsistencies in species designations. Can be subjective: The interpretation of genetic and morphological data can be subjective, leading to different conclusions about species boundaries. May not reflect ecological or functional differences: The phylogenetic species concept does not necessarily reflect ecological or functional differences between groups of organisms, which can be important in some contexts.

The morphological species concept defines a species based on physical characteristics such as anatomical features, size, shape, coloration, and other observable traits Morphological differences between individuals of the same/different species Fossil identification Helpful with extinct/extant species Can be applied to extinct AND living organisms Helpful when genetic data is unavailable

Cannot identify cryptic species Limit of variation between populations - characteristics can vary within populations, making it difficult to determine if individuals belong to the same or different species. the physical features used to distinguish between species can also overlap, leading to ambiguity in species identification. May not reflect genetic differences

Organisms that have the same resources, environmental tolerances and face the same predators Identifies species based on their role in the environment Ecological niche, behaviour, and interactions with other species Can be used to identify bacterial, archaea, or organisms that reproduce asexually Reflects ecological interactions Useful for conservation research and efforts Can reveal cryptic species

Not useful if one does now know anything about the role of the organism Difficult to apply - ecological interactions can be hard be complex Ecological differences may not reflect genetic differences and differences species can occupy similar ecological niches Limited to organisms - cant apply to bacteria and viruses as they do not have well defined ecological niches May not reflect historical relationships

Evolutionary history of populations based on the DARWIN - stated that all species are related by common ancestry All species form a MONOPHYLETIC group, or clade They are identified by synapomorphies at genetic, mental or structural levels According to this concept, species are a group of organisms that are bound by ancestors based on their morphological and genetic traits and lineage Widely applicable Reflects evolutionary history Can be applied to all organisms

Can be difficult to apply - incomplete data on lineages, etc Limited data May not reflect functional differences

In the morphospecies concept, subspecies have unique features but are not different enough to consider a new separate species. They are populations within a species that are geographically separated from each other and have some distinct morphological, behavioral, or genetic traits that set them apart from other populations within the species. Subspecies can arise due to factors such as isolation, adaptation to different environments, or genetic drift. The Biological Species Concept defines a species as a group of organisms that can interbreed and produce viable offspring. However, subspecies can sometimes interbreed with each other, producing viable offspring, but not with other populations of the same species that are further apart on the evolutionary scale. This can pose a challenge to the Biological Species Concept, as it blurs the line between what is considered a distinct species and what is not. A cline refers to the gradual variation in a particular trait or set of traits across the geographic range of a species. For example, a species of bird may have different colored feathers, with individuals in the northern part of its range having darker feathers than those in the southern part. Clines can be the result of natural selection acting on the populations in different environments, with certain traits being favored in one area over another. Natural selection can drive the evolution of subspecies and clines. Populations that are isolated from each other may evolve in different ways due to different selection pressures, leading to the development of distinct subspecies. Similarly, natural selection can act on a species' traits as they vary across its geographic range, leading to the development of clines. The variation in traits within a species can provide the raw material for natural selection to act upon, leading to adaptations to local environments and the emergence of new subspecies or the evolution of a cline.

subspecies have unique features but are not different enough to consider a new separate species. They are populations within a species that are geographically separated from each other and have some distinct morphological, behavioral, or genetic traits that set them apart from other populations within the species. Subspecies can arise due to factors such as isolation, adaptation to different environments, or genetic drift.

Prezygotic isolation (before the zygote forms) is isolation which prevents individuals from different species from mating successfully. There are different types of prezygotic isolation, such as: temporal, habitat, behavioural, gametic barrier, and mechanical. Some of these prevent mating from even occurring and some prevent fertilization after mating has occurred. Mechanisms that inhibit mating attempts: temporal, habitat, behavioural. Mechanisms that limit fertilization: gametic barrier and mechanical. Postzygotic isolation: after the zygote has formed, isolation in which the hybrid offspring of matings between members of different species either don't survive or cannot reproduce. There are two types: hybrid viability and hybrid sterility.

Allopatric - occurs when populations of a species are geographically isolated from each other and diverge over time due to different selective pressures or genetic drift. This can occur due to natural barriers like mountains, oceans, or rivers that physically separate populations, or due to human-caused changes to the landscape like habitat fragmentation or introduction of non-native species. In allopatric speciation, reproductive isolation can gradually develop between the separated populations due to genetic changes that occur in each group over time. If the populations are reunited, they may no longer be able to interbreed successfully, even if they are brought back into contact. Allopatric speciation is often driven by microevolutionary processes such as mutation, genetic drift, and natural selection acting on the separated populations. Example emergence of Darwin's finches in the Galapagos Islands. The finches are believed to have originated from a single ancestral population that arrived on the islands millions of years ago. Over time, the finches became isolated from each other due to geographic barriers such as mountains, leading to the development of distinct subspecies with different beak sizes and shapes that were adapted to their specific ecological niches. Sympatric - occurs when new species emerge within the same geographic area without any physical barriers separating the populations. This can occur due to a variety of mechanisms, such as disruptive selection, polyploidy, or ecological differentiation In disruptive selection, divergent selection pressures favor different traits within a population, leading to the emergence of two or more subpopulations with distinct traits. In polyploidy, a rare event in which an organism gains an extra set of chromosomes, can create a reproductive barrier between the polyploid individual and its parental population, leading to the emergence of a new species. Ecological differentiation can occur when populations exploit different resources or niches within the same geographic area, leading to reproductive isolation over time. An example of sympatric speciation is the emergence of the apple maggot fly in North America. The fly originally fed on hawthorn berries, but after the introduction of apples, some populations began to specialize on this new resource. Over time, reproductive isolation between the hawthorn-feeding and apple-feeding populations developed, leading to the emergence of two distinct species.

The formation of new species in populations that are geographically isolated from one another.

The formation of new species in populations that live in the same geographic area

Chromosome alterations are chromosomal mutations that involve the mutation of a long segment of DNA. Sometimes this alteration could lead to changes in the phenotype bc it changes the protein made and it leads to a different phenotype. There is a specific mutation called polyploidy that will reduce gene flow between mutant and wild-type individuals, and it does so because mutant individuals have more than two sets of chromosomes. Polyploidy occurs when an error in meiosis or mitosis results in a doubling of the chromosome number. For example, chromosomes in a diploid (2x) species may fail to pull apart during anaphase of mitosis, resulting in a tetraploid cell (4x) instead of a diploid cell. The problem: the gametes formed by diploid individuals are haploids and the gametes produced by tetraploid individuals so when they mate they form a triploid zygote and if it even develops normally and reaches sexual maturity its three homologous chromosomes cant synapse properly so all the gametes will end up with an uneven number of chromosomes so its sterile. Thus when tetraploid and diploid individuals mate they rarely produce fertile offspring and so they are reproductively isolated from each other. How do the polyploid individuals involved in speciation form? There are two general mechanisms: 1. Autopolyploid 2. Allopolyploid Speciation by polyploidization is driven by chromosome-level mutations and occurs in sympatry. Compared to the gradual process of speciation by geographic isolation or by disruptive selection in sympatry, speciation by polyploidy is virtually instantaneous. It is fast, sympatric, and common. What happens when isolated populations come into contact? If theres no prezygotic isolation then they mate. The simplest outcome is that the populations fuse over time, as gene flow erases any distinctions between them. Several other possibilities exist. • The distinctions between the populations may be reinforced if hybrids have low fitness. •Hybrid zones may be established if hybrids have intermediate fitness. • Speciation by hybridization may occur if hybrids have high fitness. If two populations have diverged extensively and are distinct genetically, it is reasonable to expect that their hybrid offspring will have lower fitness than their parents. The logic here is that if populations are well adapted to different habitats, then hybrid offspring will not be well adapted to either habitat. So if hybrids have a lower fitness, then making the hybrids is a wasted effort! So pre-zygotic isolation behaviours should be favoured, so any traits that promote this behaviour would be favoured by natural selection, and natural selection for traits that isolate populations in this way is called reinforcement.

-increase in cell size -larger plant attributes -evolution: may give rise to new species

the formation of new and distinct species in the course of evolution.

large-scale evolutionary changes that take place over long periods of time

populations are isolated because they breed in different habitats.

homology (homologous) - similarities in traits due shared ancestry Can be used to construct phylgoenies because they are from the same ancestor Analogy - similarities in traits that is not due to a shared ancestry but rather is the result of convergent evolution Can be useful to understand the functional adaptations of different organisms and construct phylogenies Analogous - term used to describe similarity in tritas that are not evolved through common ancestry. They are similar in function however, ex. Wings in birds and bats. homoplasy (homoplasious) - refers to similarity in traits that are not due to shared ancestry but rather the result of convergent evolution or other evolutionary ways.

similarities in traits due shared ancestry

similarities in traits that is not due to a shared ancestry but rather is the result of convergent evolution

term used to describe similarity in trAITSas that are not evolved through common ancestry.

A similar (analogous) structure or molecular sequence that has evolved independently in two species.

Species are a group of organisms because different species may have different criteria for determining whether they are from the same species or just two different species that may have similar characteristics. Generally, a species is a group of organisms that can interbreed and produce fertile offspring, but there are certain exceptions.

Prezygotic isolation (before the zygote forms) is isolation which prevents individuals from different species from mating successfully. There are different types of prezygotic isolation, such as: temporal, habitat, behavioural, gametic barrier, and mechanical. Some of these prevent mating from even occurring and some prevent fertilization after mating has occurred. Mechanisms that inhibit mating attempts: temporal, habitat, behavioural. Mechanisms that limit fertilization: gametic barrier and mechanical. Postzygotic isolation: after the zygote has formed, isolation in which the hybrid offspring of matings between members of different species either don't survive or cannot reproduce. There are two types: hybrid viability and hybrid sterility.

(before the zygote forms) is isolation which prevents individuals from different species from mating successfully. There are different types of prezygotic isolation, such as: temporal, habitat, behavioural, gametic barrier, and mechanical. Some of these prevent mating from even occurring and some prevent fertilization after mating has occurred. Mechanisms that inhibit mating attempts: temporal, habitat, behavioural. Mechanisms that limit fertilization: gametic barrier and mechanical.

after the zygote has formed, isolation in which the hybrid offspring of matings between members of different species either don't survive or cannot reproduce. There are two types: hybrid viability and hybrid sterility.

Allopatric - occurs when populations of a species are geographically isolated from each other and diverge over time due to different selective pressures or genetic drift. This can occur due to natural barriers like mountains, oceans, or rivers that physically separate populations, or due to human-caused changes to the landscape like habitat fragmentation or introduction of non-native species. In allopatric speciation, reproductive isolation can gradually develop between the separated populations due to genetic changes that occur in each group over time. If the populations are reunited, they may no longer be able to interbreed successfully, even if they are brought back into contact. Allopatric speciation is often driven by microevolutionary processes such as mutation, genetic drift, and natural selection acting on the separated populations. Example emergence of Darwin's finches in the Galapagos Islands. The finches are believed to have originated from a single ancestral population that arrived on the islands millions of years ago. Over time, the finches became isolated from each other due to geographic barriers such as mountains, leading to the development of distinct subspecies with different beak sizes and shapes that were adapted to their specific ecological niches. Sympatric - occurs when new species emerge within the same geographic area without any physical barriers separating the populations. This can occur due to a variety of mechanisms, such as disruptive selection, polyploidy, or ecological differentiation In disruptive selection, divergent selection pressures favor different traits within a population, leading to the emergence of two or more subpopulations with distinct traits. In polyploidy, a rare event in which an organism gains an extra set of chromosomes, can create a reproductive barrier between the polyploid individual and its parental population, leading to the emergence of a new species. Ecological differentiation can occur when populations exploit different resources or niches within the same geographic area, leading to reproductive isolation over time. An example of sympatric speciation is the emergence of the apple maggot fly in North America. The fly originally fed on hawthorn berries, but after the introduction of apples, some populations began to specialize on this new resource. Over time, reproductive isolation between the hawthorn-feeding and apple-feeding populations developed, leading to the emergence of two distinct species.

occurs when populations of a species are geographically isolated from each other and diverge over time due to different selective pressures or genetic drift.

occurs when new species emerge within the same geographic area without any physical barriers separating the populations.

polyploidy, habitat differentiation, sexual selection

Chromosome alterations are chromosomal mutations that involve the mutation of a long segment of DNA. Sometimes this alteration could lead to changes in the phenotype bc it changes the protein made and it leads to a different phenotype. There is a specific mutation called polyploidy that will reduce gene flow between mutant and wild-type individuals, and it does so because mutant individuals have more than two sets of chromosomes. Polyploidy occurs when an error in meiosis or mitosis results in a doubling of the chromosome number. For example, chromosomes in a diploid (2x) species may fail to pull apart during anaphase of mitosis, resulting in a tetraploid cell (4x) instead of a diploid cell. The problem: the gametes formed by diploid individuals are haploids and the gametes produced by tetraploid individuals so when they mate they form a triploid zygote and if it even develops normally and reaches sexual maturity its three homologous chromosomes cant synapse properly so all the gametes will end up with an uneven number of chromosomes so its sterile. Thus when tetraploid and diploid individuals mate they rarely produce fertile offspring and so they are reproductively isolated from each other. How do the polyploid individuals involved in speciation form? There are two general mechanisms: 1. Autopolyploid 2. Allopolyploid Speciation by polyploidization is driven by chromosome-level mutations and occurs in sympatry. Compared to the gradual process of speciation by geographic isolation or by disruptive selection in sympatry, speciation by polyploidy is virtually instantaneous. It is fast, sympatric, and common. What happens when isolated populations come into contact? If theres no prezygotic isolation then they mate. The simplest outcome is that the populations fuse over time, as gene flow erases any distinctions between them. Several other possibilities exist. • The distinctions between the populations may be reinforced if hybrids have low fitness. •Hybrid zones may be established if hybrids have intermediate fitness. • Speciation by hybridization may occur if hybrids have high fitness. If two populations have diverged extensively and are distinct genetically, it is reasonable to expect that their hybrid offspring will have lower fitness than their parents. The logic here is that if populations are well adapted to different habitats, then hybrid offspring will not be well adapted to either habitat. So if hybrids have a lower fitness, then making the hybrids is a wasted effort! So pre-zygotic isolation behaviours should be favoured, so any traits that promote this behaviour would be favoured by natural selection, and natural selection for traits that isolate populations in this way is called reinforcement.

There is a specific mutation called polyploidy that will reduce gene flow between mutant and wild-type individuals, and it does so because mutant individuals have more than two sets of chromosomes. Polyploidy occurs when an error in meiosis or mitosis results in a doubling of the chromosome number.

populations are isolated because they breed at different times.

populations do not interbreed because their courtship displays differ. Ex. females only recognize the songs of the males of their species

Matings fail because male and female reproductive structures are incompatible.

Matings fail because eggs and sperm are incompatible

Hybrid offspring do not develop normally and die as embryos.

Hybrid offspring mature but are sterile as adults.

Study of past and present distribution of organisms

the lack of interbreeding or little genetic mixing between organisms of the same species - results from lack of gene flow

the evolutionary process wherein a population of species diverge into two or more descendant species, resulting in once similar or related species becoming more and more dissimilar - occurs because selection, genetic drift, and mutation proceed independently in the isolated populations

natural selection for traits that isolate populations and prevent them from interbreeding

a geographic area where interbreeding occurs and hybrid offspring are common

A cline refers to the gradual variation in a particular trait or set of traits across the geographic range of a species. For example, a species of bird may have different colored feathers, with individuals in the northern part of its range having darker feathers than those in the southern part. Clines can be the result of natural selection acting on the populations in different environments, with certain traits being favored in one area over another.

when small groups of individuals colonize a new habitat (form of geographical isolation)

a physical splitting of habitat, when a large, continuous population becomes fragmented into isolated habitats (form of geographical isolation)

Background extinction Lower avg. rate of extinction observed when a mass extinction is not occurring often balanced by the emergence of new species through speciation, and it generally allows for the gradual adaptation of organisms to changing environmental conditions over long periods of time.

Mass extinction: Rapid extinction of a large number of lineages scattered throughout the tree of life Mass extinctions can also create new ecological opportunities and adaptive radiation, as the survivors of the extinction event exploit new niches and evolve new traits to fill the gaps left by the extinct organisms

Adaptations: Background extinctions generally allow for the gradual adaptation of organisms to environmental changes, as new mutations and variations are selected for over time.

• Mass extinctions can create selective pressures that are so severe and sudden that many organisms cannot adapt fast enough to survive. This can lead to the extinction of species and clades that were well-adapted to the previous environment, and the emergence of new species and clades that are better adapted to the new environment.

Lower avg. rate of extinction observed when a mass extinction is not occurring often balanced by the emergence of new species through speciation, and it generally allows for the gradual adaptation of organisms to changing environmental conditions over long periods of time.

Rapid extinction of a large number of lineages scattered throughout the tree of life Mass extinctions can also create new ecological opportunities and adaptive radiation, as the survivors of the extinction event exploit new niches and evolve new traits to fill the gaps left by the extinct organisms

Adaptive radiation

Where single ancestral species evolve into multiple descendant species that occupy different niches or habitats

Ecological opportunity: this can occur when a habitat or area is unoccupied and is available for colonization. This could be due to changes in the environment or if competitors are not around. Ex. the extinction of dinosaurs paved the way for other mammal species to evolve because the dominant forms (dinosaurs) were not there.

Morphological innovation: when new traits allow ancestral species to exploit resources and/or environments. This gives them an advantage as well. For example, the wings of birds evolved that allowed them to fly and diversify.

this can occur when a habitat or area is unoccupied and is available for colonization. This could be due to changes in the environment or if competitors are not around.

when new morpho traits allow ancestral species to exploit resources and/or environments. This gives them an advantage as well.

Rapid speciation - adaptive radiation is characterized by rapid increase of species over a small period of time Ecological diversification - adaptive radiation results in many species evolving that are adapted to different ecological niches and habitats Adaptive radiation can lead to the evolution of species that are morphologically or genetically different from each other convergent evolution

adaptive radiation is characterized by rapid increase of species over a small period of time

adaptive radiation results in many species evolving that are adapted to different ecological niches and habitats

the evolution of species that are morphologically or genetically different from each other

The relationship and temporal pattern between mass extinctions and adaptive radiation is that mass extinctions can create ecological opportunities for species and adaptive radiation.

Since the survivors of the extinction event exploit new niches and evolve new traits to fill the gaps left by the extinct organisms, they are able to evolve in the unoccupied niches.

The temporal pattern between mass extinction and adaptive radiation would be the pattern of extinction and rapid diversification of diverse organisms

Exaptation: traits such as wings, feathers etc didnt appear suddenly, in their full form and function that we see today and it may be quite different than the function of that trait during its evolutionary history for example the original function of the feather may have been insulation and its new function is flight. If natural selection selected for feathers that helped birds fly and it had some sort of benefit then that trait would increase over generations. This is how complex structures developed. (through natural selection because they provided some benefit)

shaping of a useful feature of an organism by natural selection to perform one function and the later reshaping of it by different selection pressures to perform a new function

Gene duplication when it is not deleterious can have potential phenotypic effects. It may lead to different than normal development but still be beneficial. The duplicated gene may retain original function but change in expression pattern leading to new tissues and developmental timing. Another outcome would be that the duplicated genes gain mutations and alter the protein product which could perform a valuable new function. These two outcomes could lead to the evolution of new traits which is the evolution of new phenotypes and would drive speciation.

Other outcome: duplicated gene retains original function and provides additional quantities or the mutation may prevent expression so a pseudogene is created which is a gene that produces nothing

A small number of genes control the body plans of all animals which are basically the genetic tool kit. Transcription factors (TF) and other proteins bind to specific regulatory sequences in the core and regulatory promoters. Changes in the regulation of the genes expression would result in different species having different features. For example the marine sticklebacks have spines while lake sticklebacks dont, and this is because of changes in the regulation of the Pitx1 expression in the two fish. So while they do have the same genes coding for a particular body part they have a different body plan. They would have inherited these genes from a common ancestor.

Hox genes are homeotic genes that control head to tail organization of the body and are part of the genetic tool kit. They will basically code for transcriptional factors that control when and where other genes are expressed. Changes in Hox expression are linked to large differences in body structure between different animal groups.The genes need to be expressed at specific times, if for example foot growth ends sooner then the tree-dwelling salamander will have smaller limbs whereas for the ground-dwelling salamander its longer so their limbs are bigger. This is an example of divergence and speciation due to changes in expression at the time of development.

they help determine the head to tail axis in embryonic development, and there are found in almost all multicellular organism

If different parts of the body are growing at different rates like the human head grows slower than the rest of the body. Timing is everything because if there are changes in regulation of developmental genes this could have an effect on morphology - slower development could lead to a totally different morphology. For example salamander teens live in aquatic environments and adults live on land. Heterochrony is changes in the timing of developmental events between closely related species for example the salamander and the axolot. They retain their juvenile features even as adults because of a mutation in a certain genes expression.

the growth of body parts at different rates, resulting in a change of body proportions

is defined as a developmental change in the timing or rate of events, leading to changes in size and shape. There are two main components, namely 1) the onset and offset of a particular process, and 2) the rate at which the process operates.

Phylogenetics - By constructing phylogenetic trees based on genetic and morphological data, scientists can infer the sequence of evolutionary events that led to the diversification of different groups of organisms.

Speciation (allopatric and sympatric) - These processes can lead to the formation of new species and the diversification of groups of organisms over time.

Macroevolutionary processes build on microevolutionary processes and involve the evolution of major groups of organisms over long periods of time

An evolutionary pattern in which many species evolve from a single ancestral species

the availability of new or novel types of resources

Genes that determine basic features of where a body part is.

are proteins that control the rate of transcription of genetic information from DNA to RNA.

part of an organism's body or a section of a chromosome that contains genes.

genes that control the expression of other genes

replacement of one body part with another during development

A multistep regulatory pathway in which a signal leads to activation of a series of proteins in succession, with each protein in the succession catalytically activating the next, such that the original signal is amplified exponentially.

Characteristics that persist relatively unchanged through diversification of a group of organisms and therefore remain similar in related species.

the process by which a less specialized or unspecialized cell becomes more specialized in order to carry out a specific function.

26 small bones that make up your backbone

skull

A connective tissue that is more flexible than bone and that protects the ends of bones and keeps them from rubbing together.

Endoskeleton refers to a skeleton that is located inside the body, while exoskeleton refers to a skeleton that is located outside the body.

jawed vertebrates

Anamniotes are animals that do not lay amniotic eggs, while amniotes are animals that lay amniotic eggs.

an egg that is surrounded by a membrane, allowing for development on land.

bony or cartilaginous structures that support the gills of fish and some amphibians.

second pair of jaws in the throat in some fish

growth process from conception to birth

Proportioning that gives a body a specific form.

process of transformation from one life stage to another, such as a caterpillar becoming a butterfly.

a gene that has lost its function and is no longer expressed.

Bipedalism Large brain Smaller jaw and teeth

Tool use Culture Self-awareness Language

• Development of lactose tolerance

Ability to digest lactose declines after weaning

Genetic mutation has arised that has allowed many humans to digest lactose

This mutation has become advantageous Some people still cannot digest lactose

Humans and chimpanzees are both primates that have a common ancestor many millions of years ago. They share many similarities, but humans did not DESCEND from chimpanzees. For example, humans and chimpanzees could be cousins that share grandparents, but they don't have the same parents. Cousins can look alike too and have similar characteristics, but that does not mean that they have the same parents. Likewise, humans and chimpanzees shared a common ancestor very very long ago, but they humans did not come or evolve from chimpanzees.

• Anatomical evidence Most primitive fossils were found in central and east africa, indicating that that was the region of the ancestral home of the hominins

• Genetic evidence Greatest genetic diversity is found in Africans

Migration patterns

Can be traced through fossil and genetic evidence

• Homo erectus - evolved when early hominins moved out of Africa

• Homo neanderthalensis - evolved when second migration occurred to Europe

Genetic evidence

• Genetic markers of neanderthalensis were different from african populations