evolution flashcards

extinction

the complete disappearance of a species

adaptation

structural, behavioural, physiological process that helps organisms survive and reproduce

structural adaptation

a physical feature of an organisms body having a specific function the contributes to the survival of an organism

mimicry

physical features resembling a harmful species

behavioural adaptation

actions of individuals or groups which increase the chances of survival and reproduction

migration

moving from one area to another

physiological

physical or chemical event that occurs within the body of an organism and enables survival

hibernation

metabolism of organisms slowing down

variation

differences between individuals that are determined by environmental conditions

mutations

permanent changes in the genetic material (DNA)

only source of new variations

mutations

helpful mutation

selective advantage, favoured

harmful mutation

reduces reproductive success, selected against

neutral mutation

does not result in selective advantage or diasadvantage

somatic cell mutations

mutation disappears when organism diess

sex cell mutations

can be passed onto offspring

selective advantage

a genetic advantage that improves an organisms chance of survival

natural selection

process by which characteristics of a population change over many generations

selective pressure

environmental conditions acting on a population

fitness

contribution of an individual to the gene pool of the next generation

artificial selection

selective pressure exerted by humans in order to improve/modify desirable traits

belgian blue cattle

mutation that allow for double muscling is bred into the population

wild mustard plant

selective breeding led to formation of different plants

monoculture

cultivation of a single variation of a species over a large expanse of land

buffon

common ancestry with apes, earth is older than 6000 years

malthus

populations produce more offspring than the environment can support

cuvier

paleontologist, catastrophism

catastrophism

different fossil layers were caused by natural catastrophes

anning

discovered plesiosaur

lyell

challenged catstrophism, suggested uniformatism

uniformatism

geological processes today are the same as ancient geological processes

larmack

inheritance of acquired characteristics

inheritance of acquired characteristics

species adapt to their environment and pass on adaptations to offspring

darwin and wallace

gradualism and the theory of natural evolution

gradualism

changes happen slowly and over generations

four laws of the theory of evolution

organisms produce more offspring than can survive, variation in populations is heritable, indiviuals with better adaptations produce more offspring, processes are slow and gradual

fossils

traces of remains of past life found in sedimentary rock

biogeography

the study of past and present geographical distributions of species populaions

anatomy

comparing structures within and between species

embryology

the study of early, pre-birth stages of an organisms development

fossil records

contains the remains and traces of past life buried within sedimentary rock

the law of superposition

each rock layer is older than the one above it

transitional fossis

show intermediary links between groups of organism

vestigial structures

a structure that is a reduced version of one that was functional in an organisms ancestor

evidence from biogeography

geographically close environments are populated by related species

homologous structures

similar structures, different functionn

analogous structures

structures do not have a common ancestory but have a similar function

embryology

study of early, prebirth stages of an organisms development

DNA evidence

similar genetic sequences

convergent evolution

organisms independently evolve similarities when adapting to similar environments; end up developing **analogous structures**

divergent evolution

a single species or a small group of species evolves into several different forms as a result of different environmental selective pressures,resulting in **homologous structures**

microevolution

a change in gene frequency within a population

common factors of microevolution

mutations, gene flow, non random mating, genetic drift, natural selection

mutations

randomly inroduce new alleles into a population

gene flow

occurs between two different interbreeding populations that have different allele frequencies

non random mating

individuals of a population select mates based on phenotypes

genetic drift

random change sin genetic variation from generation to generation due to chance

founder effect

a change in gene pool when a few individuals start a new population

bottleneck effect

a change in gene distribution that results from a rapid decrease in population size

common causes of the bottleneck effect

starvation, hunting, natural disasters, human activities

natural selection

survival of the fittest

stabilizing selection

favours intermediate phenotypes, reduces vairation

directional selection

favours variants at one extreme over another, common in times of environmental change

disruptive selection

favours the extremes of the range of phenotypes

microevolution

a change in gene frequency within a population

five factors of microevolution

mutations, gene flow, non-random mating, genetic drift, natural selection

mutations

randomly introduce new alleles into a population

gene flow

occurs between two different interbreeding populations with different allele frequencies

non-random mating

individuals in a population select mates based on phenotypes

genetic drift

random change in genetic variation from generation to generation due to chance, founder effect, bottleneck effect

founder effect

a change in gene pool when a few individuals start a new population

bottleneck effect

a change in gene distribution that results from a rapid decrease in population size

causes of the bottleneck effect

starvation, hunting, natural disaster, human activities

natural selection

process by which characteristics of a population change over many generations

stabilizing selection

favours intermediate phenotypes, reduces variation and improves adaptations to aspects that remain constant

directional selection

favours variants at one extreme over another, common during times of environmental change or migration

disruptive selection

favours the extremes of the range, results in elimination of intermediate phenotypes

speciation

the formation of a new species from existing species

macroevolution

formation of a new species

when does speciation occur

when members of a population change to the point where they cannot reproduce viable offspring with the original population

reproductive isolation

when there is little to no gene flow between populations over time

pre zygotic isolation mechanisms

impede mating or fertilization of eggs

behavioural isolation mechanisms

signals or behaviours that are species specific, prevent interbreeding with closely related species

habitat isolation mechanisms

two species may not encounter each other

temporal isolation mechanisms

reproductive cycles are not aligned

mechanical isolation mechanisms

species are anatomically incompatible

gametic isolation mechanisms

ensures gametes do not form a zygote

types of pre zygotic isolation mechanisms

behavioural, habitat, temporal, mechanical, gametic

post zygotic isolation mechanisms

prevents hybrid zygotes from developing into viable, fertile individuals

types of post zygotic isolation mechanisms

hybrid inviability, hybrid sterility, hybrid breakdown

hybrid inviability

genetic incompatibility stops the development of a hybrid embryo before birth, stops normal mitosis after fusion of nuclei

hybrid sterility

two species mate and produce hybrid offspring, offspring cannot reproduce

hybrid breakdown

first generation are viable and fertile, second generation are sterile or weak

types of speciation

allopatric speciation and sympatric speciation

allopatric speciation

population is split by a geographical barrier, populations become reproductively isolateds

empathic speciation

populations in the same geographical areas diverge and become reproductively isolated

causes of sympatric speciation in animals

non-random mating

causes of sympatric speciation in plants

chromosomal changes

divergent evolution

pattern of evolution where species that were once similar become increasingly distinct as they adapt to different environments

convergent evolution

similar traits arise, each species has independently adapted to similar environmental conditions