Chapter 9 class (exam3) - Ellen Flashcards
Reproductive Effort
Energy expended and risk taken for breeding
K-Selected Species
o K = Carrying capacity of environment
o Population usually at or near K
o Adapted to stable environments favoring small numbers of young that get extensive care and have low mortality
Thinking more about quality as opposed to quantity of off spring
Iteroparity:
Tend to have young at intervals
Emphasis on quality of offspring, not quantity
o Intraspecific competition tends to be great
o Typically have home range or territory
o Tend to have larger body size, slower development, longer life span
This is the category you would typically find humans in
r-Selected Species
o r = Reproductive rate of population
Adapted to fluctuation environments
High reproduction rates – quantity, not quality
• Not much care given to them
Semelparity
Tend to have young all at once (aka, big liters)
Tend to have rapid development, small body size, little parent care
• Tends to be influenced by environment and type of predators – high mortality rate for offspring
Sexual selection
A form of natural selection that favors the evolution of elaborate traits, and preferences for them by the opposite sex, if they increase the mating success of both genders
Example of fruit flies: female reproductive success does not increase with number of mates, while that of males does
Isogamy
All gametes are the same size – microorganisms, fungi, algae
Anisogamy
Gametes have different sizes – most plants and animals
Batemans’s Principle (or Reproductive Skew)
Males who mate more often have more offspring
Sex Role Reversals
in respect to which sex competes for mates and which does the choosing
Intrasexual Competition
one sex (usually female) is valuable resource for the other, which competes for access
Intersexual (epigamic) Selection
one sex is selective about mates, putting selection pressure on the other
• Sexual Dimorphism –
Differences in genders
o Males tend to be bigger (have bigger wrists, tend to be taller, ??,)
• Baboons
o Females in estrus mate with many males, but only with the dominant males when she is fertile – if there is going to be competition among males, it should be paying off
o If male reproductive success is based on number of eggs fertilized, sexual selection should favor traits which:
Allow copulation with many females
Increase the chance mates will use his sperm
Reduce the fitness of other males
• Would have to benefit troublemaker more than other males)
Submissive displays and flight are used until:
Probability of Winning X Benefit exceeds probability of Loss X Cost
p x b > q x c
• Evolutionary Stable Strategy (ESS):
o One which can’t be replaced over evolutionary time by and alternative
In one case, condition of animal determines this
In other case, genes are the determining factor
• Conditional Strategies:
Available to all and practiced depending on circumstances. Provide reproductive opportunities until circumstances improve. The alternatives are used based on the conditions. They are not genetically based and need not be equally successful – as with satellite behavior and sneak copulations.
o Scorpion flies are an example
Alternative Behaviors
Based on genetic differences and are equally fit.
o Example: Coho Salmon: two different types of male – hooknose (take longer to mature) and jack (smaller but mature sooner)
o Example: live in sponges???? – payoff of three different mating strategies is the same
Side-blotched Lizard – 3 color morphs
Orange-throated
Blue-throated
Yellow-striped throats
Orange-throated Lizard
Aggressive, mate often, large territories, easily defended against other morphs
Blue-throated Lizard
Milder temperament, more monogamous, defend small territories, lose conflicts with Orange
Yellow-striped throated Lizard
Least aggressive, no territories, resemble female color, sneak copulations, most successful fooling Orange, chased off by blue
Three morphs of side-blotched lizard produced by
3 alleles at a singe gene locus
Success of different color morphs compared to:
Orange > Blue > Yellow > Orange –> Rock > Scissors > Paper > Rock
More about Lizards
Hybrids between the morphs have intermediate behaviors
• Orange males have more testosterone, which affects aggression and throat color
• Population cycle over about 5 years from predominantly blue to orange to yellow to blue
Sperm Removal
Penile structures or behavior that remove another male’s sperm
Sharks use of sea water
Birds pecking
Lizards shape
Sperm Competition
Increased number, size, speed, cooperation
One indication of sperm competition is size of male testis
Signals
Leaves signals or stimuli like repellant odors to discourage other males (which indicate that female has already mated
Blocking
Leave mating plugs or body parts to block female genital opening
Honeybees: Male leaves genital in female, blocking any chance of other males mating
Spiders (Particular kind) male dies after copulation and remains there. Female lays eggs on dead body and babies eat it when born
Mate Guarding
Drive off other males
Intersexual/Epigamic Selection – Female Mate Choice
Reproductive behavior is influenced by female selectivity. To demonstrate that female mate choice is adaptive we must show:
- Females do not mate randomly
- Nonrandom mating patterns are not caused by male competition
- Choosy females secure reproductive advantages
• Female Selection Criteria
o Puts selection pressure on males. Criteria include:
1. Is the male a member of their species?
2. Fitness of male genes
3. Value of male parental investment (assuming that the male of this species is involved in this way
Male Parental Investment
Relatively rare because it decreases the opportunity to mate with other females. Investment is more likely if:
• 1. Food is hard to get (females need help feeding the babies)
• 2. Predators exist which adults can discourage but babies can’t (need of both parents)
• 3. Receptive females are scarce (thus, better to stay with mate)
Testing Male Genetic Quality
• Appearance - Fluctuating Asymmetry • Nuptial Gifts • Territorial Resources • Female Incitation • In species with greater male care, they may be most selective and females compete
Appearance
Color, courtship vigor, etc.
Fluctuating Asymmetry
Deviation from bilateral symmetry (study across cultures of humans shows preference for symmetry – where both sides of face and body are similar without huge variance)
Nuptial Gifts
Gifts of food or prey
Territorial Resources
Quality of territorial resources
Female Incitation
Females signal males to compete
Female seals have loud vocalization which attracts males??
In species with greater male care, they may be
most selective and females compete
(Female Preferences)
Good Genes Hypothesis:
Male characteristics signal quality of his genes and offspring he will sire
(Female Preferences)
• Healthy Mate Hypothesis:
Male courtship and appearance signal parasite load. Females avoid males who might transmit parasites to them or their offspring
(Female Preferences)
• Immunocompetence Hypothesis:
Male features (smell) signal immune system gene similarity.
(Female Preferences)
• Runaway Selection Hypothesis (R. A. Fisher):
A male signal important to the female becomes more and more pronounced until negative selection occurs due to limited survival ability. Female preference male characteristic evolve together.
Trait and preference are selective together (trait isn’t always beneficial to survival)
Female preference and male characteristic evolve together
(Female Preferences)
Chase Away Selection Theory:
Males develop characteristic that takes advantage of preexisting female sensory bias to prefer it, attracting mates even if male is inferior
Selection might then favor female resistance to this feature, causing males to devolve more of it, leading to more useless ornamentation
Examples of honest signaling: Coloration in species: Brighter colors usually indicate less infestation of parasites. In guppies, orange spot is produced with high nutrition intake, showing health. Larger males are typically more desirable (peacock with tail). Big turkey snood indicates less parasite
(Sexual Conflict)
• Infanticide:
Males killing babies or females reabsorbing embryos allows male to mate sooner, female to avoid death of offspring, so both might benefit
(Sexual Conflict)
Female Sperm Choice
Females selectively choose sperm after multiple mating
Perhaps more frequent than we realized in the wild
(Sexual Conflict)
• Forced Copulation
Once seen as result of a desirably low threshold of male sexual arousal
Disadvantageous for female and dominant males
Behavior on behalf of male is not random – directed towards productive female
Such males could produce similar successful sons, a female advantage if her daughters are not disadvantaged
