Species Content Flashcards
When Darwin went to the Galápagos Islands, why did finch species have different beaks?
Speciation, the process by which one species split into two or more species, is at the focal point of why/how these adaptations occur.
What is Microevolution?
Microevolution consists of changes in allele frequency in a population over time. Example would be the Peppered Moth.
Industrial Revolution: soot on trees caused dark moths to be more prevalent, while light moths population decreased
After pollution decreased, selection pressure reversed.
Microevolution: b/c white and black allele existed at the same time, but there was a change in allele frequency
What is Macroevolution?
Macroevolution refers to broad patterns of evolutionary change above the species level.
Speciation forms a conceptual bridge between Microevolution and Macroevolution.
What is with Similarity and DIversity?
Not all species are defined by morphological differences. Many species display massive MORPHOLOGICAL DIVERSITY, while some different species are morphologically identical.
What is the biological species concept?
Biological species concept is a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with members of other such groups.
Gene flow (interbreeding) between populations holds a species together genetically.
What is Reproductive Isolation?
Speciation is often a result of a long term reproductive isolation. Remember, if organisms cannot successfully interbreed, they are considered different species under the biological species concept.
Reproductive isolation is the existence of biological factors (barrier) that impede two species from producing viable, fertile offspring.
Hybrids are the offspring that result from mating between different species.
Isolation can occur before or after mating is attempted.
Prezygotic barriers?
Mating is prevented by geography, time, behavior, anatomy, or some other factor. NO mating is attempted or completed.
Habitat Isolation?
Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers.
Temporal Isolation?
Species that breed at different time of the day, different seasons, or different years cannot mix their gametes.
Behavioral Isolation?
Courtship rituals and other behaviors unique to a species are effective barriers to mating.
Some animals use songs to segregate between conspecifics.
Postzygotic Barriers?
Mating occurs, but proper reproduction is blocked by reduced hybrid viability, hybrid sterility, or hybrid breakdown.
Reduced hybrid viability?
Genes of the different parent species may interact and impair the hybrid’s development or survival in its environment. Even if hybrids are healthy, they may be sterile.
Hybrid Breakdown?
Some first generation hybrids are fertile, but when they mate with each other or with either parent species, offspring of the next generation are feeble or sterile.
Mechanical Isolation?
Morphological differences can prevent successful completion of mating.
Gametic Isolation?
Sperm of one species may not be compatible with eggs of another species.
