Ch.24 Flashcards
What is a species?
A group of populations whose members have the potential to interbreed in nature and produce viable, veritable offspring - but do not reproduce viable offspring with other groups
What are the two species concepts:
Biological species concept and morphological species concept
What is biological species concept?
Group of individuals that naturally interbreed and produce viable, fertile offspring
What is morphological species concept?
Group of organisms that share similar characteristics
- distinguishes a species by body shape and other structural features
What makes each of the species concepts easy to work with? Challenging to work with?
Observing and waiting for the species to breed, some may never, or other like bacteria dosen’t
what is a hybrid?
Offspring form mating between two different species
Ex: donkey (male) and horse (females)= donkey (not a species because it can’t breed/produce offspiring)
What is speciation? What are the two kind?
Gene flow is reduced in species or populations and develops into a new species
- allopatric speciation and sympatric speciation
What is allopatric speciation?
“Other homeland” gene flow is interrupted when a population is divided into geographically isolated subpopulations forming a new species
- Is caused by Geographic Isolation
What is sympatric isolation and what are the different mechanisms behind it?
Speciation occurs in populations that live in the same geographic area
- polyploidy
- sexual selection
- habitat differation
What is polyploidy and what speciation is it apart of?
Sympatric speciation
Is the chromosomal alterations in which the organism possesses more than two complete chromosome sets
- is a result of accidental cell division
- changes in chromosome number during meiosis (from 18 to 36 or 54) result in offspring not being able to mate with member of parental type
What is a result of accidental cell division?
Polyploidy
What is sexual selection?
Can lead to speciation
- when the females will choose the males with similar characteristics or appearances
What is habitat differation?
A subpopulation exploits a habitat or resource not used by the parent population
What is the mechanism to speciation?
Reproductive isolation
- allopatric
- sympatric
What is reproductive isolation?
The existence of biological factors (barriers) that impede members of two species from interbreeding and producing viable, fertile offspring
What are the two types of reproductive barriers?
Prezygotic: blocks mating/fertilizaiotn
Postzygotic: reduces hybrids becoming fertile adults
What are the Prezygotic blocks to mating/fertilization? There are 5
Habitat isolation
Temporal isolation
Behavioral isolation
Mechanical isolation
Gametic isolation
What are the postzygotic effects that reduce hybrids becoming fertile adults?
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
What is habitat isolation?
Two species live in habitats and rarely meet up, even if in the same area
Prezygotic
What is temporal isolation?
Species breed at different times of the day, season, or years
Prezygotic
What is behavioral isolation?
Courtship rituals are different between species
Prezygotic
What is mechanical isolation?
Body parts of a species are arranged in a way that if mating is attempted, the parts don’t “fit” together
Prezygotic
What is Gametic Isolation?
Sperm from one species is not able to fuse with the eggs from a different species
Prezygotic
What is reduced hybrid viability?
Hybrid offspring do not develop correctly or survive
Postzygotic
