Parasite Evolution 2 Flashcards
Q: How can parasites speciate by allopatric mechanisms?
A: Allopatric speciation occurs when populations of parasites are geographically separated, preventing interbreeding. Over time, they adapt to different environments and evolve reproductive barriers, leading to the formation of new species.
Q: How can parasites speciate by peripatric mechanisms?
A: Peripatric speciation occurs when a small peripheral population of parasites becomes isolated, often through host switching, genetic drift, or inbreeding. This isolation can lead to divergence and the formation of new parasite species associated with different hosts.
Q: How can parasites speciate by sympatric mechanisms?
A: Sympatric speciation occurs when different populations of parasites in the same geographic area specialize in different habitats or host species, leading to reproductive isolation and the formation of new species without geographic barriers.
Q: Why is sexual reproduction considered an evolutionary mystery?
A: Sexual reproduction is costly due to inefficiencies like males not producing offspring and the energy required for mate finding and meiosis. Despite these costs, it remains a dominant reproductive strategy.
Q: How might evolutionary arms races between parasites and hosts explain sexual reproduction?
A: Parasites target common host phenotypes. Sexual reproduction increases genetic variation, making offspring more resistant to parasites. This ongoing evolutionary “arms race” benefits sexual reproduction as a strategy to avoid widespread parasitic infection.
Q: How might parasites influence the evolution of male ornaments?
A: In parasite-rich environments, females may choose males with traits indicating parasite resistance. Ornaments like bright colors may signal good health and low parasite load, thus influencing mate choice and leading to the evolution of such traits.
Q: What is the Biological Species Concept?
A: The Biological Species Concept defines a species as populations that can interbreed in nature, producing fertile offspring. Reproductive barriers (premating and postmating) prevent interbreeding between different species.
Q: What are premating and postmating reproductive barriers?
A: Premating barriers prevent mating (e.g., inability to recognize mates or incompatible genitalia), while postmating barriers affect offspring viability or fertility after mating (e.g., hybrid inviability).
Q: What is allopatric speciation?
A: Allopatric speciation occurs when a population is geographically isolated, leading to independent evolution. Eventually, reproductive barriers form, preventing interbreeding, resulting in the formation of new species.
Q: What is cospeciation in the context of parasites and hosts?
A: Cospeciation occurs when a parasite and its host evolve together, leading to parallel phylogenetic trees for both. For example, the lice of pocket gophers exhibit cospeciation due to their isolated populations.
Q: What is peripatric speciation?
A: Peripatric speciation happens when a small population at the edge of a larger population becomes isolated. This isolation, often due to host switching in parasites, can lead to divergence and the formation of new species.
Q: What is sympatric speciation?
A: Sympatric speciation occurs when different populations of a species specialize for different environments or habitats within the same geographic area. This specialization leads to reproductive isolation and the emergence of new species.
Q: What is the evolutionary significance of sexual reproduction despite its costs?
A: Sexual reproduction increases genetic diversity, which helps populations adapt to changing environments, particularly in the face of parasitic pressures. This increased diversity helps avoid the negative effects of parasitic exploitation of common host phenotypes.
Q: What is Bateman’s Principle?
A: Bateman’s Principle suggests that female reproductive success is limited by the number of eggs they can produce, while male reproductive success is limited by the number of mates. Therefore, females are generally more selective in choosing mates.
Q: How does sexual selection explain the evolution of male ornaments?
A: Sexual selection suggests that males develop traits like colorful ornaments to attract females, indicating good genes or parasite resistance. These traits enhance reproductive success, even if they are costly or detrimental to survival.
