Evolution and Speciation

why is Lamark's theory not supported

why is Lamark's theory not supported

acquired traits are not inherited and passed onto future generations

why is Darwin's theory supported

variation is present in a population due to the presence of alleles

what are acquired characteristics

they develop during the lifetime of an individual

what are heritable characteristics

passed on from parent to offspring

what type of characteristics does evolution concern

heritable characteristics

what is the evidence for evolution

- DNA, RNA and protein sequences
- homologous structures
- selective breeding

why does DNA, RNA, and protein provide strong evidence for evolution

- the same genes are present in organisms which have evolved from a common ancestor
- differences in the base sequences of DNA, RNA, and proteins are the result of mutations

what is selective breeding

humans choosing plants or animals with desirable traits to breed together and produce offspring with more of the desirable traits

what are homologous structures

have a similar structure but have a different function; come from a common ancestor

what's an example of a homologous structure

wings of bats and birds, human arm, and flippers/fins

what are analogous structures

have different structure but have a similar function; no common ancestor

what's an example of an analogous sructure

bat wings + butterfly wings

what is convergent evolution

the evolution of similar structures in species not related due to a recent common ancestor

what type of structure is the result of convergent evolution

the wings of birds, bats, and insects

what is speciation

the formation of new species through evolution

what is reproductive isolation

occurs when there is a barrier which prevents individuals from reproducing

what is the common ancestor of chimps and bonobos

apes

how did the chimps and the bonobos become geographically isolated

the Congo river widened

what are the three types of reproductive isolation

- allopatric
- sympatric
- behavioral

what causes allopatric speciation

geographical isolation

what is sympatric isolation

a population divides into different species while inhabiting the same habitat

what are the 2 types of sympatric isolation

behavioural + temporal isolation

what is behavioural isolation

individuals are reproductively isolated due to behaviour

whats an example of behavioural isolation

mating behaviour in animals

what is temporal isolation

organisms reproduce at different times

what is biodiversity

the variety of organisms in an ecosystem

what is adaptive radiation

the evolution of a single ancestral species into several species, as the ancestral species spread out and become adapted to new environmental niches

adaptive radiation is what type of evolution

divergent evolution

when does adaptive radiation occur

when a single species moves to and occupies a variety of different niches

how did Darwin's finches show adaptive radiation

moved into the different niches available on the Galapagos Islands

what is a hybrid

the offspring of two different species

why are hybrids rare

the prezygotic/postzygotic barriers prevent the mixing of alleles between different species

when do prezygotic barriers occur

before fertilization

what are the four different types of prezygotic barriers to hybridization

- behavioural
- temporal
- ecological
- mechanical

what is ecological isolation

species are in different habitats

what is mechanical isolation

organisms physically can't mate

when do postzygotic barriers occur

after fertilization, the offspring isn't fertile or viable

what are the three types of postzygotic barriers

- hybrid inviability
- hybrid infertility
- hybrid breakdown

what is hybrid inviability

development of offspring is not successful (or die early)

what is hybrid infertility

hybrids are not fertile

what is hybrid breakdown

offspring can reproduce, but the second generation is weak or sterile

how many sets of chromosomes do haploids have

1 set

how many sets of chromosomes do diploids have

2 sets

how many sets of chromosomes do polyploids have

more than 2 sets

why does polyploidy result in speciation

nondisjunction, an error occurring during myosis

what types if polyploid plants are capable of reproducing

plants with an even number of sets of chromosomes as meiosis can occur with homologous pairs of chromosomes