Red Queen Hypothesis
species must constantly adapt, evolve, and run to keep up with their enemies (predators, parasites, competitors) just to survive.
Predictions:
1) Oscillations in the relative frequency of asexual lineages when parasites are present.
2) Time Lags between evolution of a new host defense and the ability of the pathogen to find a way around it.
Muller’s Ratchet
an evolutionary mechanism where asexual populations irreversibly accumulate deleterious mutations over time.
Cyclical Parthenogenesis
safeguards against environmental change by having a back-up plan for stress.
Anisogamy
in the growth rate of the lineage, the male effort is wasted on the sperm. Two zygote are made.
- In asexuall reproduction - Nothing is wasted, all effort produces four zygotes. Growth of a lineage is constrained by resources a parent can invest into biomass of offspring.
Environmental Unpredictability
the absence of expected, consistent patterns in one’s surroundings, characterized by low autocorrelation and high variance in conditions.
Dead Clade walking
a paleontological term for animal groups that survive a mass extinction event but fail to rediversify, lingering in reduced numbers before eventually going extinct.
Asexual Reproduction
Number of Niches
Parasite Load
Sexual Dimorphism
Males and females often are strikingly different in size and appearance.
Amphimixis
Alternating phase of meiosis. Three steps:
- Recombination - crossover between homologous chromosomes
- Gamete Production - Production of haploid gametes
- Gamete fusion - Gametic exchange between unrelated individuals
Intra and Intersexual selection
- Intrasexual competition: Male-male competition
- Intersexual competition: Female choice
Direct benefits
Males giving a nuptial gift to the female.
Genital plug
blocking female genital opening with a plug.
Infanticide
- The male kills the babies to enhance mating success
- The females kill any young or destroys eggs to free up males to tend her young
Amplexus
Males and females are joined in “mate guarding” with the male often behind the female. This protects her from predators and other males.
Runaway Selection
Linkage disequilibrium between a trait gene in males and a preference gene in females. Difficult to distinguish between this and Good Genes.
Handicap Principle
an evolutionary theory stating that reliable signals in animals must be costly to produce.
Sexy Sons Principle
Once a particular male advertisement is favored by a majority of females, sexual selection will automatically reinforce a preference for the fashionable trait. females choosing fashionable mates will have fashionable sons and thus more grandkids.
Cuckoldry
Fishes build a nest for mate, waits and watches, and comes in a sprays sperm (fish can sometimes look like a female).
Male-male combat
Contests between males to hold harems are common in mammals e.g. deer, lions, antelope, elephant seals. (ADD MORE)
Sensory Bias
an evolutionary theory suggesting that female mating preferences evolve as by-products of natural selection on sensory systems, rather than for direct benefits.
Traumatic Insemination
coercive mating method where male insects, such as bed bugs, use needle-like genitalia to pierce the female’s body wall and inject sperm directly into the body cavity, bypassing the genital tract.
Siblicide
the killing of an offspring by its sibling.
