Transcript Lecture 5: Animal adaptations to the environment

Animal adaptations
Outline:
• Acquisition of energy and nutrients
• Respiration
• Homeostasis
• Water balance
• Biological rhythms
• Readings: Chapter 7
Energy and nutrient acquisition
Detritivores
Herbivores
Types of herbivores
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Grazers - leaf tissue
Browsers - woody tissue
Granivores - seeds
Frugivores - fruit
Nectivores - nectar
Phloem feeders - sap
• High cellulose
(fiber), low protein
• Animals can’t
digest cellulose (no
cellulase enzymes)
• Need symbiotic
bacteria, protozoa
Ruminants
(e.g. cows, sheep, deer)
Non-ruminants
(e.g. rabbits, horses)
Coprophagy
= ingestion of feces
• E.g. Lagomorphs (rabbits, hares & pikas)
• E.g. Detritivores
N and food quality
• For herbivores, food quality increases with
increasing N content
• In animals, C:N ~ 10:1
• In plants, C:N ~ 40:1  herbivores limited
by N availability
– Highest in growing stems, leaves, buds
– Decreases as plant ages
Herbivores usually born in spring
Carnivores
• Composition of food
similar to own tissues
--> simple stomach
--> small caecum
• Need to get enough
food
Omnivores
• Feed on > 1 trophic
level, e.g. plants and
herbivores
• Diet varies with
season, life cycle
Diet breadth
1. Generalists: “polyphagous” – eat >1
prey species
2. Specialists: “monophagous” – eat one
prey species – or eat specific part of prey
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E.g. seed-eating birds
Specialists are usually
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Short-lived (active only when food is available)
Highly adapted to a specific food type (can’t use
any other)
RESPIRATION
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
HOMEOSTASIS
THERMOREGULATION
TEMPERATURE
REGULATION
TYPE OF HEAT PRODUCTION:
Endothermy: - heat from within
Ectothermy: - heat from without
Heterothermy - employ endo and ectothermy
in different situations
TEMPERATURE VARIATION:
Homeothermy - constant temperature
Poikilothermy - variable temperature
TEMPERATURE REGULATION
poikilotherms
TEMPERATURE REGULATION
poikilotherms
Operative temperature
range
TEMPERATURE REGULATION
poikilotherms
Acclimatization
TEMPERATURE REGULATION
poikilotherms
Lizards and snakes: body temperature varies only 4-5oC/day
TEMPERATURE REGULATION
homeotherms
Endothermy – ectothermy tradeoffs
Endothermy tradeoff
Conserving energy – ectothermy for juveniles
Because of their small size (high surface: volume ratio) and their need to invest energy
in growth, juvenile birds and mammals are often ectothermic, obtaining heat from their
parents.
Conserving energy – hibernation
Bears are not true hibernators; their body temperature drops only a few
degrees, and they are relatively easily awakened
Conserving energy –
countercurrent heat exchange
without
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Releasing energy –
countercurrent heat exchange
RETE
Adaptations to aridity and heat
Water balance in aquatic environments
• Freshwater organisms: hyperosmotic (water
wants to move inside of organism
• Marine organisms: hypoosmotic (water wants to
move outside of organism
Controls on activity
Human diurnal cycle
Life history strategies
Outline:
• Types of reproduction
• Mating systems
• Sexual selection
• Energy and timing of reproduction
• Offspring
• Habitat selection
• Environmental influences
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Readings: Ch. 8
A simple life history
Life history = schedule of birth, growth, reproduction & death
Types of reproduction
• Asexual or sexual
• Different forms of sexual reproduction
Simultaneous hermaphrodites
Sex change
Mating system
• Strength of bond:
– Monogamy (strong) - Promiscuity (no bond)
• Types of bonds:
– Monogamy (one-to-one)
– Polygamy (one-to-many)
• Polygyny (one male, many females)
• Polyandry (one female, many males)
POLYANDRY: African Jacana
Sexual selection
• Intrasexual selection
– male-to-male or female-to-female competition for
the opportunity to mate
Sexual selection
• Intersexual selection
– differential attractiveness of individuals
Reproduction is costly
Timing of reproduction
• Semelparity - reproduce once and die
• Iteroparous - reproduce throughout lifetime
European grasshopper,
Chorthippus brunneus
An iteroparous summer annual
Pigweed, Chenopodium album
A semelparous summer annual
Semelparous perennials
Coho salmon: a long-lived semelparous animal
• Dies after spawning (2-5 yrs)
• Overlapping generations
Semelparous perennials
Bamboo
• Both genets and ramets are semelparous.
• Genets can live for 200 years before the simultaneous flowering of all
ramets.
Parental investment
Fecundity
Fecundity
Reproductive tradeoffs
Reproductive tradeoffs
Reproductive tradeoffs
Reproductive tradeoffs
r and K strategists
For next lecture:
• Please read Chapter 9, 10, 11, 12
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