vocab

evolution - change in the heritable characteristics of a population

  • evidence can come from: the study of fossils, selective breeding of domesticated plants & animals, comparative anatomy of animals, nucleotide & amino acid sequences

sequence data - the ordered linear arrangement of molecules that carry genetic or functional info, such as DNA or protein

molecular phylogeny - is a method of providing common origin of life, by conducting comparative analysis of the base sequences of DNA, RNA & amino acids in proteins

molecular clock - a technique that utilizes the mutation rate of biomolecules, to determine the time since two species shared a common ancestor

  • species that hv few differences in their genomes & amino acids, recently split from each other

selective breeding/artificial selection - humans select the organisms that will breed together, based on favourable characteristics

  • results in rapid changes to a species’ genetic makeup, leading to evolution

  • has to occur over a long period of time before new variety in breed is produced

homologous structures - hv the same basic structure (indicating common ancestor) but hv different functions

  • ex: pentadactyl limbs of vertebrates

  • also indicates divergent evolution

    • pattern of evolution where organisms originating from same ancestral species, adapt to different environmental conditions according to pressures of natural selection

analogous structures - body parts that hv the same function, but hv different structures

  • ex: wings in birds & butterflies

  • indicate convergent evolution

    • a pattern of evolution where distantly related organisms, develop similar characteristics in response to similarities in environment/similar selection pressures

speciation - process by which new species are formed

  • species can only be formed through the splitting of 1 ancestral species into 2 or more descendant species

  • these descendant species are genetically different from each other & cannot interbreed

  • it also modifies original gene pool into separate gene pools, preventing interbreeding

    • so it leads to genetic separation

population - a group of organisms of one species, living in same area at same time

  • population of species share gene pool

reproductive isolation - barriers that prevent populations of the same species, from interbreeding &/or producing fertile offspring

  • can be temporal, geographical or behavioural

  • can result in prezygotic & postzygotic barriers

prezygotic barriers - barriers that prevent formation of zygote

postzygotic barriers - barriers that occur after zygote is formed & can include zygote variability or sterility

genetic drift - change of frequency of an existing gene variant in population due to random events

  • basically is when the population’s gene pool changes from the original gene pool

differential reproduction - situation in which certain organisms produce more offspring for next generation, compared to other organisms

allopatric speciation - evolution of one of more species from ancestral species, due to a geographical barrier

  • ex: speciation of chimpanzees and bonobos

  • can lead to reproductive isolation

sympatric speciation - evolution of one or more new species from an ancestral species while living in same geographical area

  • new species formed due to isolating mechanisms

  • behavioural or temporal isolation can lead to sympatric speciation

temporal isolation - is a result of differences in timing of reproductive cycle (such as mating seasons or gamete production)

  • species cannot interbreed, even tho they share the same geographical location

  • ex: the Magicicada tredecim (a species of cicada) reaches sexual maturity in 13 years. the Magicicada septendecim (another species of cicada) reaches sexual maturity in 17 years

    • the time to mate comes once in 221 years (13 × 17)

behavioural isolation - species develop different mating rituals over a period of time

  • prevents interbreeding because females recognize the mating ritual of a male that’s of their own species

    • ex: male fireflies use specific light patterns to attract females. male fireflies of different species display their lights differently, meaning the female of their species will recognize their light patterns, preventing interbreeding

adaptive radiation - rapid speciation of one or more species to fill various ecological niches

  • species become adapted to their respective environment, meaning they can coexist without competing for resources

    • increases biodiversity in ecosystems where there are vacant niches

    • ex: Darwin’s finches

ecological niches - position of a species within an ecosystem or community & its interrelationships with biotic & abiotic factors

hybridization - occurs when animal or plant breeds with an individual of a different species or variety

  • rarely leads to speciation

    • offspring are infertile (i think smthg to do with irregular chromosomes)

    • offspring/hybrids arent reproductively isolated from parent species

  • prezygotic & postzygotic barriers can prevent hydridization

polyploidy - condition where an organism has more than 2 sets of chromosomes

  • is a relatively simple form of speciation

  • caused due to non-disjunction of chromosomes during mitosis

Allopolyploidy/alloploidy - special case of polyploidy

  • is a hybrid & has numerous chromosome sets that’re derived from different parental species

  • normal gamete combines with polyploidy gamete

    • cell has abnormal number of chromosomes = is sterile

    • but if mated with normal gamete, viable offspring can be produced

  • if offspring cant mate with parental species but can mate with each other, leads to speciation

  • seen in knotweed (Japanese & giant knotweed)