Option D2: Species and Speciation

Definitions _________– all genes in a population at a given time _____- version of a gene ____________– the measure of a specific allele in proportion to the entire population Expressed as a proportion or _________ Allele frequency is different than the number of _____________ in a population expressing that allele

Evolution of a species Evolution of a species involves a change in the ______________of a __________ over several generations Allele frequencies are only a __________ __________, __________ or _______________ can occur (cause new entries into gene pool or exits from pool) If suitable for _________, then gene will be passed on (increasing allele frequency) In time, previous less suitable genes will be “________” of gene pool

_________ – any group of organisms that can reproduce fertile offspring Have similar ____________ (lineage) Have similar ____________________ ____________ distinct from other organisms What are some issues with this explanation of a species?

Barriers Between Gene Pools (How to get really weird animals and plants….) Genetic isolation ____________________– islands, mountain ranges, etc. ___________ (reproductive) Isolation- two species whose _______________do not intertwine ( pollen from one type of flower released before pistil of other flowers have emerged) _______________– mating behavior selects certain characteristics (mating ritual of one organism not seductive enough) Any of these will lead to new __________ given enough time

Speciation Formation of a new ________ that no longer breeds with the ______________

Allopatric Speciation When speciation occurs because of _________________ Islands are a great example of this

Sympatric Speciation _________ do overlap, but speciation occurs because of another influence (temporal, or behavioral) Could be mating ________, _______, or other courtship behavior ex. Mutation of pheremone that only attracts a few females

Polyploidy Sex cells – __________ Somatic cells - __________ ______________ – condition where there are more than 2 homologous chromosomes due to improper cell division Most common in __________ (makes them hardier) These extra chromosomes can make them _______________with the original. Can lead to _________ or ____________ of species if more favorable.

Adaptive Radiation Many similar but distinct species ___________ from one single species Happens when the organism is ___________ and in a ________ of opportunity In Darwin’s Finch the beaks adapted for ______ _____________ Lemurs in Madagascar live in _______________ (desert, trees, ground)

Convergent vs. Divergent Evolution Divergent is simply speciation due to ____________ to new _____________ (ex. Ancestor squirrel split by grand canyon to White-tailed antelope sq. and Harris’s antelope sq.) Convergent Evolution is when different organisms evolve _______________ due to similar selective __________ (marsupial anteater in Australia; mammal anteater in S.A. bioluminescence in marine organisms and fungi)

Theories on pace of evolution ___________ – species slowly change through a series of intermediate forms Supporters say __________ for enough organisms exist to show these slow _________ changes Supporters also say that you don’t see most organisms ________________ now

_______________ – rapid speciation due to new niche formation or geographic isolation Support by fossil record showing organisms (cochroaches, sharks) that have __________ significantly over millions of years Also supported by ______ in fossil record

Polymorphism When more than one ________ of a species is present in a population _________________– one form is distinctly disadvantaged __________________- if both forms provide a distinct advantage for survival

Transient Polymorphism Allele frequency changes in response to _____________ Can change back

Sickle Cell Anemia is balanced polymorphism In malaria stricken areas – both forms offer a ________ (balanced) HbA allele codes for blood cells that __________, but susceptible to ___________ HbS allele can’t carry O2, but __________ to malaria HbAHbS person gets best of __________ When not in a location where malaria is endemic, not a suitable characteristic (transient)

Cystic fibrosis Cf gene causes _______ buildup, but normal gene is susceptible to ________