Chapter 24: The Origin of Species Flashcards
What is Allopatric Speciation? What is an example of this?
speciation that occurs when populations are geographically separated
Ex. Harris/White tailed Antelope squirrels separated by the gran canyon
ex. Mosquito fish (predators and fat stored)
What is polyploidy? What is an example of this?
a chromosomal alteration in which the organisms possesses more than two complete chromosome sets that results from an accident in cell division
ex. The grey tree frog
What is SPECIATION? example?
an evolutionary process in which one species splits into two or more species
ex. California Salamander
What is a SPECIES/ BIOLOGICAL SPECIES CONCEPT? example?
a population or group of population whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable fertile offspring with other species
T or F? There is little variation in a species?
F! look at humans #diverseasfuck
What is the impact lack of gene flow on species?
can lead to formation of unique, new species
What is REPRODUCTIVE ISOLATION?
the existence of biological barriers that impede members of two species from interbreeding and producing viable, fertile offspring
What is a PREZYGOTIC BARRIER?
impedes mating between two species or hinders fertilization interspecific mating is attempted
What are the 5 types of prezygotic berriers?
- habitat isolation
- temporal
- behavioral
- mechanical
- gametic
What is HABITAT ISOLATION? example?
species occupy different habitats within the same area and therefore rarely encounter each other
ex. Thamnopfhis (one is primarily aquatic and the other spends its time on land)
ex. hawthorn vs blueberry maggot fly
these two types of flies chill and grub on different plants therefore limiting their interaction
What is TEMPORAL ISOLATION? example?
species do not breed together because they breed at different times of the day, season, or year
ex. W Skunk (late summer) and E Skunk (late winter)
ex. wood frog peak mating season is march-april and the leopard for is from April-may
What is BEHAVIORAL ISOLATION? example?
courtship rituals that attract mates and enable mate recognition are different between populations
ex. blue footed boobies have a special courtship dance unique to them
ex. electrical fish have mating electric frequencies that they send out
What is MECHANICAL ISOLATION? example?
mating is attempted but morphological differences prevent a successful completion
ex. the shells of snails that spiral in opposite directions restrict mating
ex. think of Great Danes and Chihuahua
What is GAMETIC ISOLATION? Example?
mating is attempted but the sperm of one specials cannot fertilize the egg of the other species
ex. red and purple sea urchins
What is POSTZYGOTIC BARRIERS ? example?
reproductive isolations occur after zygote is formed
What is REDUED HYBRID VIABILITY? example?
zygote forms but either
- embryo does not develop
- offspring does not survive well in its environment
ex. rana sp
ex. california salamanders- some hybridize but the hybrids do not complete development and those that do are frail
What is REDUCED HYBRID FERTILITY? example?
hybrid is healthy but is infertile and cannot reproduce
ex. liger or mule
What is HYBRID BREAKDOWN? Example?
when a viable, fertile hybrid reproduces but their offspring are feeble or sterile
ex. cultivated rice (smaller and smaller)
What is an example that is an exclusion to the Biological Species Concept?
grolar bear (polar + grizzly)
What is the MORPHOLOGICAL SPECIES CONCEPT?
characterizes species by body shape and structural features
What is the ECOLOGICAL SPECIES CONCEPT?
defines species based on ecological niche
What is the PHYLOGENETIC SPECIES CONCEPT?
defines species as the smallest group of individuals that share common ancestry
What are the two modes of speciation?
Allopatric and Sympatric
Which ones happens more quickly on average Allopatric or sympatric speciation?
Allopatric (due to different environmental pressures)
What is an autopolyploid? Example?
an individual that has more than two chromosome sets that are derived from a SINGLE SPECIES
ex. plants could double # chromosomes due to division error
What is a tetraploid?
4n
Tetraploid cannot produce offspring. T or F?
F, they are fertile but no longer able to mate with 2n organisms
What is an ALLOPOLYPLOID? Example?
a fertile individual that has more than two chromosome sets as a result of TWO DIFFERENT SPECIES interbreeding and combining chromosomes
What is HABITAT DIFFERENCIATION? example?
genetic factors enable a subpopulation to exploit a habitat/resource not used by the parent population
ex. apple/hawthorn maggot fly
What is SEXUAL SELECTION? example?
a subset of the population starts choosing the opposite sex based on specific characteristics
ex. Breeding pundamilia pundamilia - blue-tinged back
Breeding pundamilia hyererei- red-tinged back
female sexual preference of the specific colored back keeps species separate
What happens if a species with incomplete reproductive barriers come into contact with one another?
formation of hybrid zones
What are HYBRID ZONES? example?
a geographic region in which members of different species meet and mate producing at least some offspring of mixed ancestry
ex. fire bellied toad and yellow bellied toad have a clear hybrid zone in between them
What are the 3 possible outcomes of the formation of a hybrid zone?
- reinforcement
- fusion
- stability
What is REINFORCEMENT of a hybrid zone? example?
the process of NS strengthens the prezygotic barriers reducing the chances of hybrid formation
ex. pied/collard flycatcher
look similar in allopatric population but not in sympatric populations. color difference in the sympatric populations reinforces females to chose males of their own species
What is FUSION of a hybrid zone? example?
when weak reproductive barriers increase gene flow between the two species to fuse into a single hybrid species
ex. pundamilia “turbid water”
pundamilia pundamilia and pundamilia nyrererei have lost their ability to identify red or blue fins as easily due to water conditions leading to more hybridization and ultimately the creation of ONE NEW SPECIES of pundamilia
What is STABILITY of a hybrid zone? example?
when hybrids continue to be produced bc the hybrids survive and/or reproduce better than the parent species
ex. bombina hybrid toads have occurred for more than 20 years with no evidence for reinforcement or fusion
What is PUNCTUATED EQUILIBRIUM?
periods of stasis followed by sudden change
ex. the bottle neck effect
What is GRADUALISM?
change occurs gradually over long periods of time
ex. human evolution from chimp like ancestors
