BIOL 112 Unit 1 (Ch. 18 and 19)

What is evolution?

The change in organisms throughout Earth's history, where today's life is different from and descended from earlier life.

What are the two main ideas of Darwin's Theory?

1. Descent with modification 2. Natural selection

What does 'descent with modification' imply?

All present life is related through descent from a common ancestor in the past.

What is natural selection?

The mechanism for evolution, where heritable variations in traits affect survival and reproduction.

What are some misconceptions about evolution?

1. Evolution is just a theory 2. Individuals evolve 3. Evolution explains the origin of life 4. Organisms evolve on purpose 5. Species evolve into 'higher' beings 6. Evolution creates new forms by dramatic mutations 7. Evolution is completely random.

How did Darwin gather evidence for his theory?

Through observations made during his voyage on the H.M.S. Beagle, particularly in South America and the Galapagos Islands.

What is the significance of the quote by Theodosius Dobzhansky?

'Nothing in Biology Makes Sense Except in the Light of Evolution' emphasizes the foundational role of evolution in understanding biology.

What was the view of life before Darwin?

Ancient philosophies, including fixed ideal species and the scala naturae, influenced thoughts on nature and life.

Who was Jean-Baptiste Lamarck?

A biologist who linked evolution to adaptation and proposed mechanisms like 'use and disuse' and 'inheritance of acquired characteristics,' which Darwin ultimately rejected.

What did James Hutton contribute to evolutionary thought?

He proposed gradualism, suggesting that geological features are formed through slow, continuous processes.

What is uniformitarianism, and who proposed it?

Proposed by Charles Lyell, it states that the same geological processes observed today also occurred in the past at the same rate.

What role did Alfred Wallace play in the development of Darwin's theory?

He independently developed similar ideas on natural selection and co-published with Darwin in 1858.

What is the importance of heritable variation in natural selection?

Heritable variation allows for differences in traits that can affect survival and reproduction, driving the process of evolution.

What does it mean that evolution is a scientific theory?

It is a broad, well-supported explanation with predictive value, similar to the theory of gravity.

What is a common misconception about the randomness of evolution?

Many believe evolution is completely random, but it is guided by natural selection acting on heritable variations.

What did Darwin observe about species in different geographic locales?

He noted adaptations of species to their environments, which contributed to his understanding of evolution.

What is the significance of extinction in Darwin's theory?

Extinction is common and suggests that species can be replaced by descendants with new features over time.

What is the role of adaptation in evolution according to Darwin?

Adaptations help species survive in their environments, contributing to their evolutionary success.

What does the term 'scala naturae' refer to?

An ancient concept of a 'ladder of nature' where species were viewed as fixed and arranged hierarchically.

What is the difference between 'natural philosophy' and modern science?

Natural philosophy was the precursor to modern science, focusing on observation and reasoning rather than experimental methods.

How did Darwin's views differ from Lamarck's regarding evolution?

Darwin rejected Lamarck's ideas of 'use and disuse' and 'inheritance of acquired characteristics' as mechanisms of evolution.

What is the significance of Darwin's observations of the Galapagos Islands?

They provided crucial evidence for his theory, showcasing species' adaptations to distinct environments.

What is meant by 'biological species'?

A group of organisms that can interbreed and produce fertile offspring, remaining genetically separate from other groups.

What processes are hypothesized to explain how new species arise?

Processes include speciation through geographic isolation, reproductive isolation, and adaptive radiation.

What is the predictive value of Darwin's theory?

It allows for accurate predictions about the traits and behaviors of organisms based on their evolutionary history.

What is artificial selection?

The process by which farmers enhance small heritable variations through breeding.

What is the significance of Darwin's Theory of Natural Selection?

It explains the mechanism of evolution, emphasizing that more offspring are produced than can survive, leading to competition for resources.

What is meant by 'unequal reproductive success'?

It refers to the idea that individuals with advantageous traits are more likely to survive and reproduce, leaving more offspring.

What are adaptations in the context of natural selection?

Heritable traits that enhance an organism's ability to survive and reproduce in its environment.

What is an example of natural selection in action?

The development of antibiotic resistance in bacteria, such as MRSA from Staphylococcus aureus.

What are some limitations of Darwin's Theory of Evolution?

It does not explain the origin of life, how variation arises, inheritance mechanisms, persistence of variation, sudden changes in the fossil record, or the source of new traits.

What does the fossil record provide evidence for?

It shows the transition of adaptive forms over time and the existence of many extinct species.

What are homologous structures?

Anatomical features that are similar due to shared ancestry, indicating evolutionary relationships.

What are vestigial structures?

Remnants of ancestral structures that no longer serve a significant adaptive function, such as the eyes of blind cave salamanders.

What is convergence in evolutionary biology?

The process by which unrelated species evolve similar adaptations due to similar environmental pressures.

What is biogeography?

The study of the distribution of species and ecosystems in relation to geographic history.

How does molecular biology support the theory of evolution?

It shows that closely related organisms have similar DNA sequences, indicating a common ancestor.

What is the Biological Species Concept?

A definition of species that emphasizes reproductive isolation, where members can interbreed to produce viable offspring.

What is the morphological species concept?

A classification based on physical similarities and differences among organisms.

What is speciation?

The process by which new species arise, which can occur through allopatric or sympatric mechanisms.

What is allopatric speciation?

Speciation that occurs when populations are geographically isolated from each other.

What is sympatric speciation?

Speciation that occurs without geographical separation, often through mechanisms like polyploidy in plants.

What does the term 'adaptive radiation' refer to?

The rapid evolution of diversely adapted species from a common ancestor in response to new environments.

What is the significance of mutations in evolution?

Mutations are random changes in DNA that can lead to new traits, which may be beneficial, harmful, or neutral.

What is direct observation in the context of evidence for evolution?

Observing real-time changes in species, such as the adaptation of soapberry bugs to new food sources.

What is the role of transitional fossils?

Transitional fossils provide evidence of evolutionary changes and the gradual transition of species over time.

What are analogous structures?

Structures that serve similar functions in different species but do not share a common ancestry, resulting from convergent evolution.

What is the significance of the genetic code being universal?

It indicates that all living organisms share a common evolutionary heritage, as similar DNA sequences suggest relatedness.

What is the ecological species concept?

A definition of species based on the ecological niche that a species occupies.

What is the phylogenetic species concept?

A definition of species determined by evolutionary ancestry and genetic data.

What is the importance of reproductive isolation in defining species?

Reproductive isolation prevents different species from interbreeding, maintaining distinct species boundaries.

What is asexual reproduction?

A form of reproduction that does not involve the fusion of gametes.

What defines an ecological species?

A set of organisms adapted to a specific set of resources and utilizing different organic food sources.

What must occur for speciation to happen?

Reproductive isolation must occur.

What are prezygotic barriers?

Barriers that prevent fertilization from occurring.

What are postzygotic barriers?

Barriers that occur after fertilization, affecting the viability or reproductive capacity of hybrid offspring.

What is temporal isolation?

A prezygotic barrier where species breed at different times.

What is habitat isolation?

A prezygotic barrier where species are separated by different habitats.

What is behavioral isolation?

A prezygotic barrier where species have different courtship rituals or behaviors that prevent mating.

What is gametic isolation?

A prezygotic barrier where gametes of different species cannot fuse to form a zygote.

What is mechanical isolation?

A prezygotic barrier where the reproductive organs of different species are incompatible.

What is hybrid inviability?

A postzygotic barrier where a hybrid embryo fails to develop properly.

What is hybrid sterility?

A postzygotic barrier where hybrids are born but cannot reproduce.

What is hybrid breakdown?

A postzygotic barrier where second-generation hybrids are weak or sterile.

What is microevolution?

Changes in allele frequencies within a population over time.

What is macroevolution?

The processes that lead to the formation of new species and higher taxonomic groups.

What is adaptive radiation?

The evolution of many adaptations from a single point of origin, leading to the formation of multiple new species.

What is an example of allopatric speciation?

The northern spotted owl and the Mexican spotted owl, which inhabit different geographic locations.

What role does female choice play in speciation?

Female choice can maintain gene flow barriers between species by favoring mates of the same species.

What is aneuploidy?

A chromosomal error where there are too many or too few chromosomes.

What is autopolyploidy?

A condition where an organism has two or more complete sets of chromosomes due to errors in meiosis.

What is allopolyploidy?

A condition resulting from the combination of gametes from two different species.

What is the significance of species-specific binding proteins?

They are crucial for gametic isolation, as they allow sperm to recognize and fertilize the eggs of the same species.

What are chromosomal errors during cell division that can lead to sympatric speciation?

Aneuploidy and polyploidy.

What is polyploidy?

A condition where a cell or organism has extra sets of chromosomes.

What is the significance of polyploidy in plants?

It has been very important for speciation in plants but is rarely found in animals.

What is punctuated equilibrium?

A model where species exhibit large changes in a short period followed by long periods of stasis.

What is gradual speciation?

A model where species diverge gradually through time with small steps.

What is the Hardy-Weinberg Principle?

It states that allele and genotype frequencies in a population remain stable in the absence of evolutionary influences.

What are the conditions for Hardy-Weinberg equilibrium?

No mutations, random mating, no selection, large population size, and no gene flow.

What is a gene pool?

The total collection of alleles in a population.

What is genotypic frequency?

The proportion of each genotype in a population.

What is allelic frequency?

The proportion of each allele in a population.

What role do mutations play in genetic variation?

They can create new alleles, which may be harmful, neutral, or beneficial.

What is sexual recombination?

The process that produces genetic diversity among offspring through crossovers, independent assortment, and random fertilization.

What is the significance of phenotypic variation?

It is mostly genetic but can be influenced by environmental factors.

What is the role of point mutations?

They can lead to the creation of new alleles, potentially affecting phenotype.

How can harmful alleles be hidden in a population?

They may be masked in heterozygotes, where the dominant allele is expressed.

What happens to neutral alleles if the environment changes?

They may become adaptive and increase the likelihood of leaving offspring.

What is the classic example of sympatric speciation due to polyploidy?

The grey tree frog, Hyla chrysoscelis and Hyla versicolor.

What does the Hardy-Weinberg equation describe?

It describes a population at equilibrium and is used to determine genetic makeup: p² + 2pq + q² = 1.

What do p and q represent in the Hardy-Weinberg equation?

p represents the frequency of the dominant allele, and q represents the frequency of the recessive allele.

What is the significance of the Hardy-Weinberg equilibrium?

It serves as a null hypothesis; if actual ratios differ from expected ratios, the population is evolving.

What are the main mechanisms of microevolution?

Natural selection, genetic drift, founder effect, bottleneck effect, and gene flow.

How does natural selection affect populations?

It acts non-randomly on phenotypes, changing allelic and genotypic frequencies, leading to adaptation.

What is the founder effect?

It occurs when a few individuals start a new isolated population, leading to a gene pool that differs from the original.

What is genetic drift?

Genetic drift is the random change in allele frequencies, often occurring in small populations, which can reduce genetic diversity.

What is the bottleneck effect?

It occurs when an event drastically reduces population size, resulting in a random gene pool and loss of alleles.

What is gene flow?

Gene flow is the movement of alleles into or out of a population, typically through migration or dispersal.

What is relative fitness?

Relative fitness is the reproductive success of an individual compared to others in the population.