Chapter 24 Origin of Species Flashcards
(27 cards)
What is a morphological species?
Species that are distinct in form & structure from other groups.
What are ecological species?
Share distinct resources, share the same niche and relevant towards ecosystem modeling. ECOLOGICAL ROLE
What are biological species?
Species are groups of organisms that can interbreed and produce viable, fertile offspring.
What leads to the formation of new species (speciation)?
The accumulation of genetic differences that prevent gene flow between two populations.
What are prezygotic isolation mechanisms?
Barriers that prevent mating or fertilization between species.
What are postzygotic isolation mechanisms?
Barriers that occur after fertilization, reducing hybrid success.
What type of reproductive barrier exists between Mimulus lewisii and Mimulus cardinalis?
Mechanical isolation — a prezygotic barrier due to differences in flower structure.
What environmental factors influence genetic variation in mangrove killifish?
They live in fluctuating environments (like tidal pools), where changing conditions create selective pressures that help maintain genetic variability.
Does self-fertilization eliminate genetic diversity in K. marmoratus?
No — while self-fertilization increases homozygosity, some heterozygosity is retained, especially due to occasional cross-fertilization.
How does cross-fertilization affect genetic diversity?
Cross-fertilization introduces new genetic combinations, helping to preserve genetic variation and counteract the effects of inbreeding.
How did the Amazon molly originate?
It is a hybrid species, formed from the mating of a male from a related species (like the sailfin molly) and a female Amazon molly.
What is gynogenesis, and how does it relate to Amazon mollies?
Gynogenesis is a form of reproduction where sperm triggers egg development but doesn’t contribute genetic material. Offspring are genetically identical to the mother.
What kind of offspring do Amazon mollies produce?
All-female offspring, since reproduction is clonal and no male genetic input is involved.
Where is species differentiation seen in the ring species Ensatina salamanders?
Species differentiation occurs at the ends of the ring, where the geographically distant populations no longer interbreed, despite being connected by a chain of interbreeding neighboring populations.
What is speciation?
bifurcation of an ancestral species into two species.
Three types of speciation?
- Allopatric speciation
- Parapatric speciation
- Sympatric speciation
What is allopatric speciation?
Speciation that occurs due to geographic isolation.
What is parapatric speciation?
Speciation that happens when populations are adjacent (no physical barrier), but gene flow is limited due to environmental gradients or partial isolation.
What is sympatric speciation?
Speciation that occurs within the same geographic area—without physical separation.
Happens due to factors like polyploidy (especially in plants), sexual selection, or niche differentiation.
What happens when species with incomplete reproductive barriers come into contact in a hybrid zone?
When two species with incomplete reproductive isolation meet, they may form a hybrid zone—a region where individuals from the different species interbreed, producing hybrid offspring.
What is adaptive radiation?
rapid diversification from the common ancestor
What is allometric growth (rate)?
Allometry refers to the differential growth rates of different parts of an organism.
What is heterochrony?
Evolutionary changes in the timing or rate of developmental events.
Heterochrony (timing) - What is paedomorphosis?
Development slows or stops early (retention of juvenile traits in adults).
