Evolutionary Theories Flashcards

Flashcards based on lecture notes covering evolutionary theories, natural selection, and adaptation.

What type of process did Darwin propose for evolution?

A variational process of evolution proposed by Darwin.

What is the term for the tree of life diagram showing the descent of species?

Phylogeny

What kind of evolutionary process did Lamarck propose?

Transformational process

What was Lamarck's ladder-evolution hypothesis?

That species transform into more complex forms over time, with simpler forms continually reappearing.

What did Charles Lyell reveal that impacted Darwin's understanding of evolution?

Discovering that the Earth is millions of years old

What is homology?

Similarity in structure due to inheritance from a common ancestor.

What is natural selection?

A mechanism for gradual evolution of differences; population matches the aspect of the environment from which competition arises

What is adaptation?

The process by which a population optimally matches the aspect of the environment from which competition arises.

What part of the Evolutionary Tree represents common ancestors?

Interior nodes

When examining an evolutionary tree, what should you focus on?

Focus on the ordering of the branching events and ignoring the timing.

What is a monophyletic group (clade)?

A group of organisms that share a common ancestor and all of its descendants.

What is a paraphyletic group?

A group of organisms that share a common ancestor but do not include all of its descendants.

What is a polyphyletic group?

A taxonomic group of organisms that share similar traits but do not share a common ancestor

What is species relatedness?

How closely two or more species are connected through their evolutionary history

What is an unrooted phylogeny?

A diagram that shows the evolutionary relationships between organisms without indicating a common ancestor or the direction of evolution

What is a rooted phylogeny?

A phylogenetic tree that has a single branch representing a common ancestor of all the species in the tree

What is a polytomy?

A node in a phylogenetic tree where more than two lineages branch off from a single ancestral lineage

What are sister taxa?

Two organisms that branch off the same node.

What is Synapomorphy?

Shared derived character

What is Homoplasy?

The character evolves independently on two branches

What is Symplesiomorphy?

The character was present in the common ancestor but got lost along some branches

What is an outgroup?

A species (or group of species) that is related to the clade of interest but which branched off earlier in evolutionary history.

What does parsimony suggest about evolution?

The most parsimonious tree has the lowest number of evolutionary changes.

According to the Parsimony Method, what should you do when data is unattainable?

When data is unattainable go simple

When building phylogenies what can characters be?

Character states can be nucleotides along a DNA sequence

What is bootstrapping?

Random sampling method to find the best tree

What is phylogeny/ cladogram?

A graph that shows how well sequence data fits

What is a phenotype?

The observable characteristics of an organism.

In artificial selection, who or what is the selective agent?

The selective agent is the human breeder.

What are the components of natural selection?

Individual members of a population differ from one another, and some of these differences are transmitted from parent to offspring; Individuals with certain traits are more successful than others at surviving and reproducing in their environment (higher fitness)

What is breeders equation?

R = S x h2

What is adaptation?

A population response to a change in the environment.

What is acclimation?

An individual response to a change in the environment.

What is coevolution?

The process in which evolutionary changes to traits in species 1 drive changes in species 2, feeding back into one.

What is sexual selection?

A form of natural selection which acts on heritable variation in traits that directly influence reproduction, mating, and fertilization.

What is good genes hypothesis?

Extravagant traits signal male genetic quality; Choosing physically attractive males will lead to more attractive sons and more grandchildren

What is exaptation?

An adaptation that later is selected for a different function.

What is sexual conflict?

Selection in which mates are gained in one sex at some cost to the other.

How can you affect phenotypic variation?

Chromosomal recombination is possible; the production of gametes (by meiosis

What does Quantitative Trait Locus (QTL) analysis do?

Links two types of information, phenotypic data (trait measurements) and genotypic data (molecular makers)

What are H-W principle allele frequencies?

P = Frequency of allele b; 1= 1-p = Frequency of allele W; BB= p2; BW= 2pq; WW= q2

How does drift affect allele frequencies?

Causes genetic variation to decrease within populations, Some alleles are fixed, some are lost, heterozygosity decreases; causes populations to diverge by chance; increases genetic variation between generations

What effect do mutations have on fitness?

The fitness effects of mutations can be studied in a controlled lab; mutations affect fitness by altering protein function; mutations can range from positive-neutral-deleterious-lethal

What is Linkage Disequilibrium?

2 alleles occur together on the same chromosome more often than can be random chance

How is Linkage Disequilibrium determined?

Frequency of AB) x (frequency of ab) - (frequency of Ab) x (frequency of aB)

What are the two population speciations?

Dispersal and vicariance

What is Dobzhansky- Muller genetic incompatibility?

Negative epistasis between alleles; Essential mechanism that makes reproductive isolation and speciation irreversible

What two forces together predict adaptive radiation?

Ecological opportunity and sexual selection

What type of mutations does The Ka/Ks (dN/dS) test of selection look for?

Nonsynonymous mutations that are deleterious will be eliminated by purifying selection

What are primiate characteristics?

Dextrous hands, large brains, range of motion, color vision, etc

What are Hominins?

Members of the human side of the phylogenetic split from the chimpanzees

What two important processes were key to human expansion?

Natural selection and adaptation

Where did the EPAS1 gene in Tibetans come from?

It was acquired by interbreeding prior to the divergence

Why do genetic diseases persist?

Genetic Drift can drive deleterious mutations to fixation; Deleterious Alleles may persist in mutation-selection balance; Deleterious alleles may persist due to heterozygote advantage

What is linkage disequilibrium equation?

(F of AB) x (F of ab) - (F of Ab) x (F of aB)

Why is the global challenge of HIV to the human species so important?

Causes a dramatic decline in population health

What must a HIV variant do the be successful?

Replicate faster, be better at escaping the host immune defense, be able to infect more host cells

What is a prime mover of evolution?

Cooperation often acts as the driving force in evolution

What does Haplodiploidy entail?

The males of the species are clones and get either 1 of the 2 alleles from the mom; The females of the species also get either 1 of the 2 alleles from mom But also get the 1 allele from dad (dad only has 1 allele to give!!)

What is a Ribozyme?

RNA with catalytic enzyme properties

What can hypercycle mutations cause?

Altruistic Mutation; Defection Mutation

According to The tree of Life, what three domains emerged?

Individually diverged bacteria, archaea, and then eukaryotes

What are the two methods to multicellularity?

Aggregation: Coming together; Foregoing cell division: Staying together

What ate Hanschen individuality criteria?

Genetic Uniqueness, Genetic homogeneity, Division of labor, Indivisibility, Physiological unity and integration, spatial/temporal boundaries, group-level adaptions

What is pleiotropy?

One gene has several functions

What is Epistasis:

The phenotype for a certain gene depends on the presence of another gene

What is Antagonistic pleiotropy?

Trade offs

What are Paralogs?

A gene that is the same via duplication

What is the difference between orthologous and paralogs?

Orthologous- relation by speciation events; Paralogs- relation by duplication events

What does the Evolution of Complexity entail?

Evolution of new kinds of individuals; Hierarchical organization of life (Nestedness); Increased body cell; Division of labor; Increase in cell types; Spatial Patterns; New Genes

What is the paradox of sex?

Sex is costly; Sex is common

How can Sex induce variation?

Mixes, creates new combinations, reduces LD

What are the haploid disequilibrium outcomes?

Coupling Disequilibrium- AB and ab: extremely fit and extremely unfit individuals, slows evolution; Repulsion Disequilibrium- Ab and aB: both groups are equally and positively fit, accelerates evolution

According to Muller's Ratchet, how does sex help populations?

Sex helps populations deal with deleterious mutations

In The Red Queen Parasite Model, what disadvantage does the asexual clone encounter?

These parasites increase in frequency, resulting in a selective disadvantage to the asexual clone, which now decreases in frequency and often is lost in the population

What is Peto's Pardox?

The average number of mutations that occur during cellular division increases linearly with the size of the organism

What is the Meiossis timeline?

Present in LECA; evolved duplicated gene in prokaryotes

Is life immortal

Healthy genes; adaptation

What is Darwinian vs modern definition of evolutions?

Darwinian def. Evolution is descent with modification; Modern def. Evolution is the change in allele frequencies over time

What is adaptation in terms of generations?

A group level response over time

What is the Naturalistic Fallacy?

It is a fallacy to think that just because something is natural it is good or right; Evolution is not a moral system

What are limits of natural selection?

There are sexual conflicts or some individuals cannot express the best factors of ALL their traits/We have limited resources

What graphs show when and how long to adapt to pressures?

Trees; homoplasy and heritability also natural selection