Practice Questions BIOA01 Midterm Review

Evolution

The process by which living organisms change over generations through the accumulation of heritable changes in their traits.

Common ancestor

The shared lineage that connects all life on Earth, both past and present, to a single ancestral species.

Theory of evolution

A well-substantiated explanation of how and why species change over time, supported by extensive empirical evidence.

Scientific theory

A comprehensive and well-substantiated explanation of a natural phenomenon, supported by a large body of evidence.

Scientific law

A concise statement that describes a fundamental relationship between observable phenomena.

Law of natural selection

The fundamental process driving evolution, describing the mechanism by which certain traits become more or less common in a population over time.

Timescales of evolution

The vast periods of time, ranging from millions to billions of years, over which evolutionary changes occur, making it challenging for humans to intuitively grasp the gradual, cumulative nature of the process.14. Descent with modification:Descent with modification refers to the process of species evolving and changing over time through the passing down of traits from parent to offspring. It is a key concept in the theory of evolution by natural selection. Two ways we can assess descent with modification are:

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Analyzing the DNA or genetic material of different species to identify similarities and differences, which can provide evidence of shared ancestry and evolutionary changes.1. Descent with modification:The concept in evolution that species descend from common ancestors but undergo changes over time.

Comparative Anatomy

The study of anatomical structures of different species to find similarities that indicate shared ancestry.

Comparative Genetics

Genetic analysis, including DNA and protein sequence comparisons, to reveal genetic similarities and differences among species.

Fossil record

A chronological record of preserved remnants of past life on Earth, used to study how species have changed over time.

Transitional forms

Fossilized organisms that exhibit characteristics of both ancestral and descendant species, providing evidence for evolutionary transitions.

Archaeopteryx

A key transitional form between birds and reptiles, exhibiting both feathered wings and reptilian features.

Vestigial characters

Anatomical structures or traits in an organism that have lost their original function through evolution but are retained in a reduced or non-functional form.

Appendix

A vestigial structure in humans, believed to be a remnant of a larger cecum used for digesting plant material.

Coccyx (Tailbone)

A vestigial bone at the base of the human spine, thought to be a remnant of a functional tail in primate ancestors.

Vestigial genes

Remnants of genes that were functional in ancestral species but have accumulated mutations that rendered them non-functional in humans.

Oldest microfossils

Microscopic fossils found in rocks from Western Greenland and Western Australia, dating back to around 3.5 to 3.8 billion years ago, representing ancient prokaryotic organisms.1. Fossil record:A comprehensive collection of preserved remnants and imprints of organisms from Earth's past.

Geological time

The vast expanse of time spanning billions of years, which allows for the understanding of the gradual processes that have shaped the diversity of life on Earth.

Morphological changes

Changes in the physical characteristics and anatomical features of organisms over different geological time periods, traced through the study of fossilized remains.

Descent from a common ancestor

Evidence of shared ancestry among different species, inferred through comparisons of anatomical, genetic, and fossil evidence.

Homology

Similarities in traits or characteristics among different species due to a common ancestry.

Structural homology

Similarities in the pentadactyl limb structure (having five digits) in vertebrates, such as humans, bats, and whales.

Genetic homology

Similarities in DNA sequences between species, indicating a shared genetic code.

Developmental homology

Embryonic similarities among different species, such as the presence of gill pouches in fish, reptiles, birds, and mammals.

New species derived from pre-existing species

Evidence supporting the theory of evolution by natural selection, demonstrating common ancestry and the interconnectedness of all life on Earth.

Difficulty in observing evolution in action

Evolution occurs over long time scales and is often gradual, making it challenging to directly witness genetic changes within a human lifetime.

Darwin's discoveries in Patagonia and the Galápagos Archipelago

Crucial evidence for his theory of evolution by natural selection, based on observations of variations in species adapted to specific environments.

Megatherium

An extinct genus of giant ground sloths that lived during the Pleistocene epoch.

Glyptodon

An extinct genus of large, armored mammals related to modern armadillos, living during the Pleistocene.1. Artificial selection:The intentional breeding of plants and animals by humans to promote desirable traits.

Examples of artificial selection

Breeding dogs for specific characteristics and cultivating crops with higher yields.

Influence of artificial selection on the development of the theory of natural selection

It showed Darwin that selection pressures applied by humans could lead to significant changes in traits, similar to natural selection in the wild.

Thomas Malthus

An economist who argued that human populations tend to grow exponentially while resources grow linearly, leading to competition for limited resources.

Influence of Thomas Malthus on Darwin's deduction of evolution by natural selection

Darwin applied Malthus's principles to populations in nature, leading him to recognize the role of competition and struggle for survival in natural selection.

Natural selection referred to as Darwin's Dangerous Idea

It challenges traditional religious and philosophical views by explaining the diversity of life without invoking a divine creator.

Darwin's Postulates

1. Variation exists within populations. 2. Some of this variation is heritable. 3. Individuals with certain heritable traits have a higher chance of surviving and reproducing. 4. Over time, the traits that confer a survival advantage become more common in the population.

Peter & Rosemary Grant

Evolutionary biologists who conducted long-term studies on Galápagos finches.

Significance of Peter & Rosemary Grant's work on Darwin's finches

Their research provided direct evidence of natural selection in action, documenting changes in beak size and shape in response to environmental shifts.

Impact of the drought of 1977 on our understanding of natural selection

The drought resulted in a scarcity of food, creating strong selective pressures. Finches with beaks better suited to the available food sources had higher survival rates, illustrating the power of natural selection.

Tribulus (caltrop)

A type of plant with spiky seeds.

Role of Tribulus in the story

The finches typically ignore Tribulus seeds because their beaks are not adapted for eating them. These seeds are an example of a resource that the finches did not exploit until other food sources became scarce during the drought.

Change in G. Fortis on Daphne Major

G. fortis populations exhibited a shift towards individuals with deeper beaks. This change was driven by natural selection, as birds with deeper beaks were better equipped to crack open tougher seeds, which became a more abundant food source.

Slight change in beak depth as evidence of evolutionary change

A slight change in beak depth from one generation to the next indicates that heritable traits are being passed down and are subject to natural selection. Over time, such small changes can accumulate, leading to significant evolutionary shifts.

Bmp4

A gene involved in beak development.

Role of Bmp4 in Darwin's finches

Changes in Bmp4 expression are associated with variations in beak size and shape in finches, making it a potential driver of adaptive evolution.

Candidate gene

A gene that is considered to play a role in a particular trait or phenotype and is investigated for its potential involvement in evolutionary processes.1. Evolution:The process of change in allele frequencies over time in populations.

Individuals

Single organisms that do not undergo evolution.

Goal-directed

Evolution does not have a predetermined goal or direction.

Microevolution population.

Macroevolution

Larger-scale changes such as speciation and the diversification of major taxonomic groups.

Population

A group of individuals of the same species living in the same geographic area and capable of interbreeding.

Gregor Mendel

An Austrian monk and scientist known for his work on pea plants, which laid the foundation for modern genetics.

Population genetics

The study of how genetic variation changes within and between populations over time.

Mutation

A change in an organism's DNA sequence, important for introducing genetic diversity in evolution.

Types of mutations

Point mutations, insertions, deletions, and chromosomal rearrangements.

Lenski's experiment

Long-term experimental evolution of E. coli demonstrating the power of natural selection and adaptation over time.

Genetic drift

Random fluctuation of allele frequencies in small populations, influencing evolution.

Bottleneck

Drastic reduction in population size, leading to reduced genetic diversity.

Founder effect

Establishment of a new population by a small group, also leading to reduced genetic diversity.

Gene flow

Exchange of genetic material between populations, important for introducing new genetic variation and preventing divergence.

Impact of gene flow

Studying how gene frequencies change between connected populations to observe the impact of gene flow.1. Natural selection:The process by which individuals with advantageous traits survive and reproduce more, leading to those traits becoming more common in a population.

Fitness

An individual's ability to survive and reproduce in its environment.

Relative fitness

Compares the reproductive success of one genotype to others in the same population.

Directional selection

Favors one extreme phenotype.

Stabilizing selection

Favors intermediate phenotypes.

Disruptive selection

Favors both extremes, leading to the divergence of traits.

Darwin's finches

Provide an example of directional selection when drought favors finches with larger beaks.

Nonrandom mating

Involves individuals choosing mates based on certain traits.

Inbreeding

Increases homozygosity.

Assortative mating

Reinforces specific traits.

Sexual selection

Favors traits that enhance an individual's ability to attract mates and reproduce.

Intersexual competition

Involves members of one sex choosing mates based on certain traits.

Differential investment by males and females

Refers to the different energy and resource investments that males and females make in raising offspring.

Fundamental asymmetry of sex

The idea that in many species, females typically invest more in offspring than males.

"Good genes"

Refers to genes that increase the offspring's fitness.

Sexual dimorphism

Differences in appearance or traits between males and females of the same species.

Sex role reversal

When males and females switch traditional reproductive roles.

Seahorses

Represent an example of sex role reversal, validating the assumptions of sexual selection theory.1. Role reversal:A situation where males carry and give birth to offspring, as seen in seahorses.

Sexual selection theory

A theory that explains how certain traits and behaviors are favored in the process of mate selection.

Parental investment

The amount of time, energy, and resources that a parent invests in raising offspring.

Ornaments

Physical traits or characteristics that are used to attract mates, often displayed by males in various species.

Balancing selection

A type of natural selection that maintains genetic diversity by favoring multiple alleles in a population.

Balanced polymorphism

A situation where two or more distinct alleles for a gene are maintained in a population over time due to balancing selection.

Heterozygote advantage

When individuals with two different alleles for a gene have a higher fitness than individuals with two identical alleles.

Negative frequency-dependent selection

Favors rare phenotypes over common ones, as seen in the left-mouthed scale-eating fish.

Adaptation

A trait or characteristic that has evolved over time in a population because it enhances the organism's fitness in its environment.

Competitive optimum

Natural selection often leads to the evolution of traits that optimize an organism's ability to compete for resources, mates, and survival within its specific ecological niche.

Compromises

Adaptations often involve trade-offs and balancing various factors due to limited resources or conflicting demands.

Lag in environmental change

Adaptations can lag behind environmental change because the process of evolution through natural selection takes time.

Legless lizard

A reptile that is not a snake but belongs to a different family, retaining features like eyelids and external ear openings.

Tree of Life

A metaphorical representation of the evolutionary relationships between all known species on Earth, illustrating their common ancestry and evolutionary history.

Carolus Linnaeus

A Swedish biologist known for his contributions to the development of modern biological classification.

Classification

The process of organizing and categorizing living organisms based on their shared characteristics.

Taxonomy

The science of naming, defining, and classifying organisms.

Linnean taxonomy

A hierarchical system of classification named after Linnaeus, grouping organisms into categories like kingdom, phylum, class, order, family, genus, and species.

Nested hierarchy

A hierarchical system where smaller, more specific categories are contained within larger, more general categories, reflecting evolutionary relationships among organisms.

Taxonomic groupings

Kingdom, Phylum, Class, Order, Family, Genus, Species (from largest to smallest).

Speciation

The process by which populations of a common ancestor evolve into distinct, reproductively isolated groups, leading to the formation of new species.

Genetic isolation

The process by which populations become unable to interbreed due to geographical, behavioral, or genetic barriers.