bio 152

species

a group of individuals that can exchange genetic material through interbreeding to produce fertile offspring.

biological fitness

a measure of the extent to which an individual's genotype is represented in the next generation

biological adaptation

a trait that leads to greater fitness in an individual

the process of a population becoming better adapted (better suited compared to other versions)

biogeography

study of how species are distributed across the planet

natural selection

process where traits that increase fitness become more common over generations

genetic variation

heritable variations in a population

main sources are mutations and recombination

gene pool

all the alleles present in all individuals in a population

populations

all the individuals of a given species that live and reproduce in a particular place

one of several interbreeding groups of organisms of the same species living in the same geographical area

somatic mutations

a mutation that occurs in somatic cells

germline mutations

a mutation that occurs in eggs or sperm or in the cells that give rise to these

neutral mutations

genetic changes that have no effect or negligible effects on the organism, or whose effects are not associated with differences in survival or reproduction

deleterious mutations

genetic changes that are harmful to an organism

advantageous mutations

genetic changes that improve their carriers' chances of survival or reproduction

allele frequencies

the proportion of a specified allele among all the alleles of a gene in a population

fixed

describes the situation in which all individuals in a population are homozygous for the same allele of a particular gene

genotype frequency

the proportion of a specified genotype among all the genotypes for a particular gene or set of genes in a population

Hardy-Weinberg Equilibrium

a state in which allele and genotype frequencies do not change over time, implying the absence of evolutionary forces.

it also specifies a mathematical relationship between alleles frequencies and genotype frequencies

selection

the retention or elimination of mutations in a population of organisms

genetic drift

a random change in the frequency of an allele due to the statistical effects of finite population size

non-random mating

mate selection biased by genotype or relatedness (tendency towards inbreeding or outbreeding)

fitness

a measure of the extent to which an individual's genotype is represented in the next generation

Modern Synthesis

the current theory of evolution, which combines Darwin's theory of natural selection and Mendealian genetics

stabilizing selection

a form of selection that selects against extremes and therefore maintains the status quo

directional selection

a form of selection that results in a shift of the mean value of a trait in a population over time

artificial selection

a form of directional selection similar to natural selection, but with selection done intentionally by humans, usually with a specific goal in mind, such as increased milk yield in cattle

disruptive selection

a form of selection that operates in favor of extremes and against intermediate forms, selecting against the mean

sexual selection

a form of selection that promotes traits that increase an individual's access to reproductive opportunities (increases fitness, but not necessarily survival)

intrasexual selection

a form of sexual selection involving interactions between individuals of one sex, as when members of one sex compete with one another for access to the other se

intersexual selection

a form of sexual selection involving interaction between males and females, as when females choose from among males

bottleneck effect

an extreme, usually temporary, reduction in population size that may result in marked loss of genetic diversity and, in the process, genetic drift

founder effect

a type of genetic drift that occurs when only a few individuals establish a new population

migration

the movement of organisms from one place to another, including the movement of individuals from one population to another

gene flow

the movement of alleles from one population to another through interbreeding between members of each population

species concepts

description on how to draw the line between species

biological species concept

the concept that "species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups"

most widely used and accepted definition of a species (does not apply to asexual organisms)

morphological species concept

the idea that members of the same species usually look like each other more than like other species

unified species concept

species are independent evolutionary units

they diverge and evolve independently from one another

universal species concept

A species is a group of populations that is evolving. Test as many other species concepts as possible and see where the evidence points to.

hybrid offspring

the offspring produced by a cross

sometimes applied specifically to interbreeding between two closely related species

hybridization

interbreeding between two different varieties or species

niche

the combination of traits and habitat in which a species exists

ecological species concept

the concept that there is a one-to-one correspondence between a species and its niche

phylogenetic species concept

the idea that members of a species all share a common ancestry and a common fate

pre-zygotic

describes factors that prevent the fertilization of the egg (behavioral isolation, temporal isolation, gametic isolation, geographical isolation, ecological isolation)

post-zygotic

describes factors that cause the failure of the fertilized egg to develop into a fertile individual (genetic incompatibility)

allopatric

describes populations that are geographically separated from each other

subspecies

allopatric populations that have yet to evolve even partial reproductive isolation, but which have acquired population-specific traits

dispersal

the process in which some individuals colonize a distant place far from the main source population

vicariance

the process in which a geographic barrier arises within a single population, separating it into two or more isolated populations that are isolated from one another

adaptive radiation

a period of unusually rapid evolutionary diversification in which natural selection accelerates the rate of speciation within a group, with new species adapted for specific niches

co-speciation

a process in which two groups of organisms speciate in response to each other and at the same time, producing matching phylogenies

sympatric

describes populations that are in the same geographic location

instantaneous speciation

speciation that occurs in a single generation

speciation

splits in a phylogeny

lineage

lines on a phylogeny

node

in phylogenetic trees, the point where a branch splits, representing the common ancestor from which the descendant species diverged

phylogenetic tree

a tree-like diagram representing a hypothesis about the evolutionary relationships among populations or species

sister groups

groups that are more closely related to each other than either of them is to any other group

taxon (taxa)

a named taxonomic group at any rank, such as a species, a genus, or a family

monophyletic (clade)

describes groupings in which all members share a single common ancestor not shared with any other species or group of species

genus

a group of closely related species

family

a group of closely related genera

class

a group of closely related orders

phylum (phyla)

a group of closely related classes, defined by having a distinct body plan

kingdom

group of closely related phyla

domains

of the three largest limbs of the tree of life: Eukarya, Bacteria, and Archaea

bilateral symmetry

arrangement of an organism's body parts to the left and right halves on a central plane

homologous

describes characters that are similar in different species because of descent from a common ancestor

analogous

describes similar character that evolved independently in different groups as a result of similar selection pressures

synapomorphies

a shared, derived character, the basis of cladistic phylogenetic reconstruction

cladistics

phylogenetic reconstruction on the basis of shared evolutionary changes in characters, often called synapomorphies

parsimony

choosing the simplest hypothesis to account for a given set of observations

opting for the tree requiring the fewest evolutionary steps

radiation

a period of raid speciation, usually caused by natural selection

mass extinctions

a catastrophic drop in recorded diversity, which has occurred five times in the past 541 million years (50 to 95% of ALL species)

extermophiles

able to survive conditions lethal to most other life

horizontal gene transfer

the transfer of genetic material between organisms that are not parent and offspring

endosymbiotic theory

eukaryotes evolved through a process whereby different types of free-living prokaryotes became incorporated inside larger prokaryotic cells and eventually developed into mitochondria, chloroplasts, and possibly other organelles.

generation time

avergage time between two generations

conjugation

the direct cell-to-cell transfer of DNA, usually in the form of a plasmid

transformation

the conversion of cells from one state to another, as from nonvirulent to virulent, when DNA released to the environment by cell breakdown is taken up by recipient cells

transduction

horizontal gene transfer by means of viruses

photoheterotrophs

an organism that uses light to generate ATP but that must obtain carbon in organic form

chemoautotrophs

a microorganism that obtains its carbon by the fixation of carbon dioxide, using energy derived from chemical reactions, not from sunlight

symbiosis

a close interaction that has evolved between species that live together, often independently

symbioant

a member of symbiosis

endosymbiosis

a symbiosis in which one partner lives within the other

unicellular eukaryotes

protists

multicellular eukaryotes

animals, fungi, plants

antibiotic resistance

bacterium can undergo a mutation and resist an antibiotic, and the resistant bacterium can continue to divide, forming a population of antibiotic resistant bacteria

haploid

describes a cell with one complete set of chromosomes

diploid

describes a cell with two complete sets of chromosomes

zygote

the diploid cell formed by the fusion of two gametes

algae

a photosynthetic protist

protozoa

a heterotrophic protist

protists

an organism with cells having a nucleus but lacking other features specific to plants, animals, and fungi

superkingdoms

one of the seven major groups of eukaryotic organisms, classified by molecular sequence comparisons.

bulk flow

the movement of fluids over long distances through organisms due to pressure differences

gap junctions

a type of connection between the plasma membranes of adjacent animal cells that permits materials to pass directly from the cytoplasm of one cell to the cytoplasm of another

plasmodesmata

connections between the plasma membranes of adjacent plant cells that permit molecules to pass directly from the cytoplasm of one cell to the cytoplasm of another (plants ONLY)

meristems

A discrete population of actively dividing, totipotent plant cells located at the tip of stems and roots and produce cells that allow plants to grow in length, while lateral ones surround stems and roots and produce cells that allow growth in diameter.