UCSD BILD 3 Midterm 1

descent with modification

Main idea in Origin of Species: all organisms evolved from a common ancestor, but diverged over time

adaptation

Main idea in Origin of Species: organisms lived in different habitats over millions of years, so they accumulated modifications to better live in those environments

natural selection

Main idea in Origin of Species: this is the mechanism for evolution

domain, phylum, family

Three extra classifications we use today different from Linnaeus

Cuvier

Studied fossils and rock layers, first to speculate an age of reptiles before mammals, and established fact of extinction

Hutton

Father of modern geology, observed that very slow geological processes observed in modern day must have been operating in the past (gradualism)

Lyell

Popularized Hutton's idea of gradualism, called it uniformitarianism, influenced Darwin greatly

Lamarck

Suggested the inheritance of acquired characteristics (incorrectly), such as passing down muscles built over a lifetime

Malthus

Wrote "Essay on the Principle of Population", influenced Darwin about the struggle to survive due to competition within a growing population

Cape Verde Islands

Darwin found a ring of white sedimentary rock containing marine shells about 15 meters above sea level

Brazil

Darwin's first exposure to wet tropical environments with their astounding diversity, making him question if God created every single little difference in organisms

Punta Alta

Darwin discovered the bones of extinct giant mammals in the cliffs, that are similar to currently living organisms

Falkland Islands

Darwin realized that a fox on the island suggested some type of land bridge; also had a lot of brachiopod marine fossils

Chile

Darwin found fossil marine shells at 12k ft; witnessed a volcanic eruption/earthquake that raised coastal shelf by 8 ft (geological changes over time)

Galapagos Islands

Darwin realized that different islands supported distinct species and subspecies within certain lineages (tortoises, finches)

barnacles

After returning from the voyage, Darwin extensively studied these sea organisms, and saw tons of variation within one species and multiple species

pigeons

After returning from the voyage, Darwin bred these organisms to perform artificial selection

disperse

After returning from the voyage, Darwin studied plants and animals could do this, allowing them to reproduce on their own

finches

After returning from the voyage, Darwin studied these, which he collected on the Galapagos Islands, leading to ideas on adaptive radiation

adaptive radiation

The diversification of species originating from a common ancestor to fill a wide variety of ecological niches

Wallace

published his own theory of evolution by natural selection about the same time as Darwin

Weisman

German zoologist, observed that heritable traits pass from generation to generation via material in gametes

Mendel

Austrian monk, observed that parents pass discrete units of information to offspring: concepts of genes, recessive traits, dominant traits

microevolution

Change in the genetic composition of a population across generations (short time scales)

macroevolution

Change in the composition of species over time

fossil

Any trace of an organism that lived in the past, can be used to test evolutionary hypotheses: extinction, succession, and transitional forms

extinction

Controversy about this theory ended with discovery of the Irish elk (largest deer that ever lived), which was different from any extant animal

succession

Fossils from one region similar to extant organisms from that same region

transitional forms

Organisms that have characteristics of both ancestral and modern forms of species, can reveal how evolution occurred

tetrapods

Tiktaalik roseae fossil discovered, a large scaly fossil fish, potentially a transitional from between fish and these

birds

Archaeopteryx is a transitional form between dinosaurs and these (had feathers, could not fly)

vestigial organs

Functionless or rudimentary organ in one species that has important function in other species (goosebumps, wisdom teeth, appendix, coccyx)

structural

An example of this type of homology is the fact that mammalian forelimbs have the same basic structure despite different function

homology

Similarity due to inheritance of traits from a common ancestor

developmental

This type of homology sees similarities during development (e.g. fetus) despite differences in adults

molecular

This type of homology sees similarities among organisms at this level, such as in genetic code

analogous

These type of structures share a common function but not similar origins (evolved independently)

convergent

This type of evolution describes how analogues arise due to evolution of similar features independently in different evolutionary lineages, usually from different developmental pathways

phenotype

Characteristics of an organism as a result of genes and the environment

genotype

Genetic composition of an organism

norm of reaction

The set of phenotypic expressions of a genotype under different environmental conditions (e.g. range of height of a tree)

phenotypic plasticity

Environmentally induced variation in the phenotype

obligate

Expression of this type of trait is determined by genes only

facultative

Expression of this type of trait is determined by genes and the environment

acclimation

reversible phenotypic changes in an individual organism in response to changing environmental conditions

developmental response

Irreversible phenotypic change in response to environmental cues

artificial selection

Natural selection imposed by humans for a specific goal, as in the breeding of crops, animals

mutation

Change in genetic material of an organism, the only source of new genetic variation (has to be heritable to alter the population); comes from copying errors in cell division, and exposure to chemicals/radiation

sexual recombination

This is a factor for variation in a population, it "reshuffles the deck" by creating new genetic combinations

relative fitness

The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

heritability

Proportion of variation in at trait that is genetic = genetic variation / phenotypic variation

Grants

Their finch work in the Galapagos concluded that natural selection and evolution can be measured in natural populations, that evolution is dynamic, and does not create the perfect organism because the environment is always changing

directional

In this type of selection, extreme phenotypes are the most fit (changes mean, decreases variation)

stabilizing

In this type of selection, intermediate phenotypes are the most fit (no changes in mean, decreases variation)

disruptive

In this type of selection, both extreme phenotypes are more fit than intermediate ones (no changes in mean, increases variation)

frequency dependent

In this type of selection, phenotype fitness varies depending on the frequency it occurs (can be negative or positive)

Hardy-Weinberg Equilibrium

p^2 + 2pq + q^2 = 1

Allele frequencies are p and q

Exists in a population that is not evolving, assumes:

- No selection

- Mating is random

- Population is large enough that there are no chance events that can change allele frequencies

- No gene flow

- No mutation

- Everyone produces the same number of offspring

- All members of population breed equally

genetic drift

Change in genetic composition of a population caused by chance events

- Sampling error: the error caused by getting alleles from a sample instead of the whole population

- Evolution can occur due to random chance

- Occurs more often in smaller populations

- Decreases proportion of heterozygotes in a population

bottleneck effect

A sudden change that drastically and randomly reduces the population size, leading to a change in allele frequencies

Pingelap

Example of bottleneck effect/genetic drift occurs on this island, where 1 in 12 people have achromatopsia

founder effect

A small number of individuals start a new population and the gene frequencies of the new population are different from the original

gene flow

Transfer of alleles into or out of a population as a result of the movement of fertile individuals or their gametes (e.g. pollen)

- Reduces genetic differences among populations

- Counteracts loss of variation from drift

- Can oppose natural selection and adaptation

mean fitness

freqAAfitAA + freqAafitAa + freqaa*fitaa

sexual dimorphism

Differences in physical characteristics between males and females of the same species

secondary sexual characteristics

Traits that differ between the sexes but do not play a direct role in reproduction

intersexual selection

Individuals of one sex (usually female) are choosy in selecting their mates

intrasexual selection

Competition among individuals of one sex (often males) for mates

good genes

In this hypothesis, females prefer traits that indicate the genetic quality of the male

sexy sons

In this hypothesis, females prefer traits that increase the likelihood that her sons will get lots of mates (and make more offspring)

direct selection

In this hypothesis, females prefer traits that maximize their immediate survival and reproductive ability

diploidy

This allows for the preservation of genetic variation by allowing recessive deleterious alleles to "hide out" in heterozygous genotypes

heterozygote advantage

Occurs when heterozygotes have a higher fitness than do both homozygotes, can maintain allelic variation in populations (e.g. sickle cell vs. malaria)

speciation

Divergence of a lineage to create new species (bridges micro and macroevolution)

biological species concept

Group whose members can interbreed in nature and produce viable, fertile offspring

- United by gene flow

- Differentiated by reproductive isolation

prezygotic barriers

Type of reproductive isolation where individuals never mate

physical

This type of reproductive isolation is a prezygotic barrier because mates can never meet

habitat

This type of reproductive isolation is a prezygotic barrier because mates are active in different parts of their environment

temporal

This type of reproductive isolation is a prezygotic barrier because mates have different reproductive seasons

behavioral

This type of reproductive isolation is a prezygotic barrier because mates do not recognize each other as viable partners

mechanical

This type of reproductive isolation is a prezygotic barrier because mates do not have compatible reproductive organs

gametic

This type of reproductive isolation is a prezygotic barrier because male and female gametes are not compatible

postzygotic barriers

Type of reproductive isolation where mating occurs but offspring not viable or fertile

morphospecies concept

The definition of a species as a population or group of populations that have measurably different anatomical features from other groups

phylogenetic species concept

A definition of species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life (sharing the same genetic code)

allopatric

Type of speciation when reproductive isolation occurs because populations are geographically separated either by vicariance or dispersal

vicariance

Type of allopatric speciation, divergence of two populations due to physical barrier (e.g. river)

dispersal

Type of allopatric speciation, separation of a small population away from a large, ancestral population

sympatric

Type of speciation that occurs in geographically overlapping populations

habitat differentiation

Type of sympatric speciation due to appearance of new ecological niches

polyploidy

Type of sympatric speciation due to condition in which an organism has extra sets of chromosomes, often leading to "instantaneous speciation" due to incompatibility

living fossil

No morphological change over very long time periods; no close living relatives

isotopes

Varieties of an element with different mass due to different numbers of neutrons in the nucleus

carbon-14

This is used to find the ages of human artifacts or things that were once living

uranium

Used for dating the age of the Earth

background

This type of extinction occurs at a normal rate

mass

This type of extinction occurs when a large percentage of species go extinct within a short period of time due to some large scale event

Precambrian

Era in which oxygen concentrations increase, eukaryotes appear, and multi-cellularity arises

endosymbiosis theory

The theory that the eukaryotic cell evolved via the engulfing of one prokaryotic cell by another

Paleozoic

Era starts with Cambrian explosion, ends with the largest mass extinction in history

Cambrian explosion

A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history, new innovations initiated new lifestyles (e.g. predation)