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Testing hypothesis 2. Predict: If high T b harms pregnant females, then 35 o treatment should have lower survivorship lower growth in mass or length Predict: If high T b harms embryos, then 35 o treatment should have more abnormalities smaller size at birth (mass, SVL)

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testing hypothesis 2
Testing hypothesis 2
  • Predict:If high Tb harms pregnant females, then 35o treatment should have
    • lower survivorship
    • lower growth in mass or length
  • Predict:If high Tb harms embryos, then 35o treatment should have
    • more abnormalities
    • smaller size at birth (mass, SVL)
    • smaller sizes at 9 days
results effects on females
Results: Effects on females
  • None
  • Survival = 100% for all
  • Growth not significantly altered by treatment
  • High temperature has no effect on females performance
results abnormalities
Results: Abnormalities
  • Of 15 females in each treatment:
    • at 35oC … 4 females produced 1 or more abnormal or dead offspring
    • at 32oC … 1 female produced 1 or more abnormal or dead offspring
    • in Treg … no females produced abnormal or dead offspring
  • abnormalities rather rare, hard to say much
conclusions
Conclusions
  • High temperature actually increases development rate of embryos
  • However, high temperatures reduce mass and SVL at birth
  • Effects of high temperatures remain for up to 9 days after birth
  • This size effect is probably sufficient to affect offspring fitness (survival)
overall conclusions
Overall conclusions
  • Pregant females actively regulate at a lower Tb because of negative effects of high temperature on offspring fitness
  • How might this evolve?
    • Quantitative trait: Tb when pregnant
    • Fitness differential (S): females with Tb = 32OC
physiological ecology summary
Physiological EcologySummary
  • Ecology of individuals
  • Adaptive value of physiological traits
  • Homeostasis (e.g., thermoregulation)
  • “How” vs. “Why” questions
  • Costs and constraints (e.g., S. merriami)
  • Benefits related to fitness (e.g., S. jarrovi)
behavioral ecology
Behavioral Ecology
  • Another aspect of the ecology of individuals
  • The relationship between the living and nonliving environment and the actions of animals
topics within behavioral ecology
Topics within behavioral ecology
  • Foraging - how environment influences choice of what, how, when, where to eat
  • Social systems - how environment influences how individuals interact with conspecifics; living in groups
  • Sex and mating systems - environmental determinants of mating and reproduction
behavioral ecology focuses on adaptation and evolution
Behavioral ecology focuses on adaptation and evolution
  • Main focus is on the adaptive value of observed traits in a given environment
  • There can be questions of both how and why concerning behavior
  • In both cases, approach is similar to that seen in physiologial ecology (costs, benefits, constraints)
living in groups
Living in groups
  • Many animals live in groups with conspecifics
    • Birds form feeding flocks, migrating flocks
    • Herds of herbivorous mammals
    • Schools of fish
    • Insect aggregations (e.g., monarch butterflies)
  • What determines group size?
  • What are benefits and costs?
major benefits of group living
Major benefits of group living
  • Improved foraging success
  • Improved defense against enemies
  • Improved ability to cope with the physical environment
improved foraging success of groups
Improved foraging success of groups
  • Improved location of food
  • Individuals observe one another and improve their chances by watching others succeed
  • e.g., blue herons - prefer to forage in areas where other herons are already foraging
  • species feeding on large ephemeral clumps of resources (e.g., fish)
improved foraging success of groups15
Improved foraging success of groups
  • Improved probability of capture
  • mammals - most predators fail more often than they succeed
  • lions
    • success rate double for 2 lions vs. 1 lion
improved foraging success of groups16
Improved foraging success of groups
  • Ability to take larger prey
  • group hunters - lion, spotted hyena, wolves, wild dog, kill prey >= their own mass
  • solitary hunters - leopard, coyote, striped hyena, kill prey < their own mass
improved defense against enemies in groups
Improved defense against enemies in groups
  • Improved detection of predators
  • More eyes, noses, ears
  • greater probability of detecting predator
  • Bird flocks -- large flocks take flight when hawks are farther away
  • Advantage does not increase with group size indefinitely
improved defense against enemies in groups18
Improved defense against enemies in groups
  • Improved ability to deter a predator
  • Groups attack predator (e.g., gulls)
  • Chemical deterrence (e.g., pine sawflies)
  • Warning coloration - bigger signal
improved defense against enemies in groups19
Improved defense against enemies in groups
  • Confusing a predator
  • Many targets in a group -- hard to hit one
  • Shoals of fish attacked by squid
  • success rate of squid
    • single fish > small shoal > large shoal
improved defense against enemies in groups20
Improved defense against enemies in groups
  • Dilution effect
  • One predator takes one victim
  •  group size,  individual’s prob.(death)
  • Have conspecifics nearby so they can be the victim
  • Effect reduced if :
    • >1 individual taken
    • prob.(attack) increases with group size
forming selfish herds
Forming selfish herds
  • Group = cooperation?
  • Animals may move to position conspecifics between themselves and predators
  • If predators take nearest animal, moving to center benefits individual
  • Result: form tight groups because each individual selfishly seeks middle
forming a selfish herd29
Forming a selfish herd
  • Point: Forming groups does NOT imply cooperation
  • Each individual may be acting selfishly for its own benefit
  • Effects on the group as a whole secondary
improved ability to cope with the physical environment in groups
Improved ability to cope with the physical environment in groups
  • Improved ability to thermoregulate
  • e.g., musk ox, roosting bats
    • groups minimize cost of thermoregulation by clustering
    • clustering reduces heat loss
benefits of group living weighed against costs
Benefits of group living weighed against costs
  • Aggressive interactions between conspecifics
  • Sharing resources that may be scarce
  • Nonexclusive access to mates
  • Disease transmission
mating systems
Mating systems
  • Who mates with whom
  • Environment influences the mating system
sexual selection
Sexual Selection
  • Selection that arises when individuals of one sex (usually ) gain advantages over other members of that sex in acquiring mates.
  • Darwin originated the concept
  • Now viewed as a subclass of natural selection
two kinds of sexual selection
Two kinds of sexual selection
  • Intrasexual selection: typically - competition
  •  compete for access to 
  • Darwin “power to conquer males in battle…”
  • Weapons; large, strong, aggressive 
two kinds of sexual selection37
Two kinds of sexual selection
  • Intersexual selection: typically  choice of mates
  •  prefer  with particular characters
  • Darwin “power to charm females…”
  • showy structures, behaviors
mating systems39
Mating systems
  • Description of who mates with whom?
  • Differential investment of  and 
  •  - high cost gametes
    • produce few gametes
    • choosy
    • low variation in reproductive success
  •  - many, low cost gametes
    • produce many gametes
    • indiscriminant
    • high variation in reproductive success
mating systems40
Mating systems
  • Promiscuous
    • all individuals mate with a number of mates
    • marine invertebrates, many insects, some fish, nearly all plants
  • Polygynous
    •  mate with >1;  mate with 1 at a time
    • many mammals, some birds, many insects, many amphibians
mating systems41
Mating systems
  • Polyandrous
    • mate with >1;  mate with 1 at a time
    • a few birds, a few insects, a few fish
  • Monogamy
    • 1 with 1
    • many birds, some mammals, a few insects, some fish
mating systems depend on ecological conditions
Mating systems depend on ecological conditions
  • Territories for mating, breeding (e.g., birds)
  • Resources (e.g., food, nest sites)
  • Defense against enemies
  •  gets material benefits from choosing certain 
mating systems depend on ecological conditions43
Mating systems depend on ecological conditions
  • Resources uniformly spread
    •  gain most by seeking unmated 
    • no sharing resources
    • Monogamy
  • Resources patchy (best males--best patches)
    •  may gain most by seeking best  (best patch) even if he has a mate
    • Polygyny
polygyny threshold

monogamous

2nd 

FEMALE FITNESS

5

4

3

2

1

Males

TERRITORY QUALITY

Polygyny threshold
ecology and mate choice
Ecology and mate choice
  • Distribution of resources influences mate choice
    • all territories good, resources uniform - monogamy
    • territories vary a lot in resources - polygyny
ecology and mate choice47
Ecology and mate choice
  • What about cases where there is no material benefit?
  • Why should females prefer showy males?
  • Male quality
    • colors, ornaments, songs, displays etc. are costly
    • “good” males can pay that cost
    • handicap principle
    • Presumes “quality” is heritable
parasite mediated sexual selection hamilton zuk hypothesis
Parasite-mediated sexual selection (Hamilton-Zuk Hypothesis)
  • Why should females prefer showy males?
  • Enemies (specifically parasites)
    • parasitized males have reduced showiness
    • showy colors  males resistant to local parasites
    • resistance to parasites heritable
    • benefit of choosing those males  resistant offspring
  • ectoparasites of birds - gnaw feathers
  • endoparasites - general reduction in vigor
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