Lec 11 Species and Speciation Flashcards
What is the definition of multiple species?
involvement of two or more species
What are pre-zygotic barriers to reproduction?
prevents mating or fertilization if mating occurrs
What are post-zygotic barriers to reproduction?
prevents hybrid offspring of 2 species from developing into fertile adults
How is speciation related to evolutionary isolation?
Species can emerge from evolutionary isolation due to reproductive barriers or genetic interbreeding
Define allopatric speciation
Prevented reproduction from geographic isolation of a previously breeding population; the populations are isolated and can no longer mate
Define parapatric speciation
Geographically continuous populations occur over EXTREMELY vast distances experience divergence
Define sympatric speciation
Speciation occurs among populations that live in the same geographic area
Name the challenges of defining clearly delineated species (ex: ring species)
It’s a classification challenge. Continuous populations can interbreed over large geographic areas except where the populations rejoin.
Where is that point at?
Define allopatric speciation using vicarience
The population is split by a geographic barrier that gradually occurs over time
Define allopatric speciation using dispersal
Random movement to new areas result in such a long distance that the populations no longer mate and are no longer continuous/are fundamentally different.
Differentiate allopatric speciation using vicarience and dispersal
Vicarience separates the populations gradually over time
Dispersal events happen suddenly
Define morphological species concept:
organisms from the same species share the longest possible evolutionary history and are on the same path.
share similar phenotypic characteristics
Define genetic species concept:
organisms from the same species share similar DNA than those of different species due to a long shared evolutionary history
share similar molecular characteristics (share DNA in reproduction)
Define biological species concept:
species from groups of organisms interbreed and produce offspring that are reproductively isolated from other species
test of genetic information and same evolutionary path
What similarity is found between the biological, morphological, and genetic species concept?
members of the same species are linked by shared ancestral history by exchanging genetic information
How are phylogenies related to the hypothesis of species divergence?
We can construct a phylogeny to observe how close or related species are from their ancestors dependent on the amount of time that has passed
define adaptive radiation
Periods of evolutionary change where organisms form a variety of new species with adaptations accustomed to certain niches
define competitive exclusion
Two species can never be perfectly and equally successful at utilizing a resource so the more successful competitor excludes the second from its niche
define niches
Specific biotic and abiotic resources used by a species
How does speciation conclude species concept testing?
Theoretical predictions based on evolution and biodiversity are concluded when phylogenetic trees, mtDNA testing or (biological) species concept(s) provide needed evidence
What limitations are present in the biological species concept?
hybrids (2 species mate), extinct organisms, and asexually reproducing organisms
What limitations are present in the morphological species concept?
tremendous variation within species and don’t understand what variation could be relevant
What limitations are present in the genetic species concept?
tremendous variation within species and don’t understand what variation could be relevant
define speciation
process where populations attain reproductive isolation
define reproduction isolation
biological barriers that impede members or different species from interbreeding to produce viable offspring
What is mechanical isolation?
morphological differences (often genital) causes mating incompatibility
What is an example of mechanical isolation?
variation in duck penis and vaginal tract morphology
complicated genitals decrease likelihood of mating
Is mechanical isolation a pre-zygotic or post-zygotic barrier?
Pre-zyogtic barrier. If mating cannot occur, fertilization does not occur
What is behavioral isolation?
Behavioral differences prevent mating through incorrect courtship displays or the opposite sex cannot recognize mating signals
What is reduced viability?
Hybrids fail to develop or are unlikely to survive
Barrier to exchange to genetic material
Why is reduced hybrid viability a genetic barrier?
The hybrid is so unhealthy compared to it’s non-hybrid peers
Is reduced hybrid viability a pre or post-zygotic barrier?
Post-zygotic barrier
Why is reduced hybrid viability a post-zygotic barrier?
Fertilization has already occurred.
What is hybrid sterility?
Hybrid offspring are perfectly healthy but are fully or partially sterile
Is behavioral isolation/mate recognition a pre- or post- zygotic barrier?
Pre-zygotic
What is temporal isolation?
When different species are reproductively available at different times (days, seasons, or years)
What does allopatric mean?
Allo= other
Patric = homeland
Is temporal isolation a pre-zygotic barrier or post-zygotic barrier?
Pre-zygotic
When does allopatric speciation occur?
The populations accumulate so many genetic differences that they couldn’t mate, even if the barrier moved
What is an example of allopatric vicarience?
Squirrels and chipmunks split over time by grooves in Grand Canyon, they attain mutation separately. Now we have two different breeds of chipmunks in the North and South.
What is an example of allopatric dispersal?
A group of iguanas live in the Galapagos island. A storm blew them from one side of the island to another. Furthermore, they made it there from sheer randomness. Over time, they reproduce with another species and create a totally different species. Populations 1 and 2 are fundamentally different as time has passed between the two.
What does parapatric mean?
Para=through
Patric=homeland
When does parapatric speciation occur?
Individuals at either end of distribution are functionally isolated from one another. Thus, they experience distinct selective pressures based on environment.
What does parapatric speciation result in?
The divergence of the species populations range on extreme ends.
When does adaptive radiation occur?
after mass extinctions or when new areas become colonized
What happens to the inferior species among competitive exclusion?
They go locally extinct or utilize different resources
Define crypsis
Camouflage
Define mimicry
uniform color similar to another species
Define ring species
continuous populations that span over large geographic areas to form a ring where they interbreed except where they rejoin
What is the classification challenge for ring species?
There is no clear distinction between where one species starts and another species starts; we can only acknowledge they exist in a continuum of differentiation
What is sympatric speciation a combination of?
Sexual selection and environmental pressures
Define punctuation equilibrium for speciation:
rapid bursts of speciation followed by little change
Define the gradual model for speciation:
species steadily diverge over time which leads to substantial differences in model period
Define Adaptive Radiation
common ancestoral population that has massive bursts of diversification to result in new species with specialization to niches
Define Niche:
full suite of living or non-living resources required by organism for survival and reproduction
When does Adaptive radiations occur?
After mass extinctions or when new areas are colonized
Why don’t Adaptive Radiations result in multiple species who are identical in resource usage (niche)?
Species compete with one another
Define competitive exclusion:
2 species will never be perfectly equally successful at utilizing a resource
Define resource partitioning:
Similar species coexist in an area if they use different sets of similar resources or same resource at different times
