Mammalogy Final
Terms
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- definition of social system
- -aggregations of intercommunicating conspecifics bounded by areas with low frequency
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three types of space partitioning in social systems
-KNOW PICTURES -
-colonial social systems
-communal social systems
-dispersed social systems - five types of social systems
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-asocial
-simple aggregations
-reproductive social units
-simple social systems
-complex social systems - asocial systems
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-minimal contact - only lactation and breeding
-aggressive behavior in all other interactions
-males and females defend territories
-Lynx rufus, puma concolor, Thomomys - what's special about thomomys social system
- -habitat is clumped but there is no nonaggressive contact except for lactation and breeding
- simple aggregations
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-groups of individuals with no cohesion
-group membership fluid and ephemeral
-aggregations occur around clumped resource
-Bovidae - reproductive social units
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-pair bonds form (may last season or be permanent)
-usually no dominance heirarchy
-may see monogamy which may be obligate or facultative
-Peromyscus californicus (obligate monogamy) - simple social systems
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-groups persistent and stable
-dominance heirarchy, no division of labor
-may be age class, gender, lots of variation
-Myotis - nursery colonies with only adult females and young, with nearby bachelor colonies
-Equus burchelli - harem of females - complex social systems
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-stable and persistent groups
-membership in groups spans generations
-establishment of dominance heirachies
-division of labor - three types of complex social systems
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-monogamous family groups
-polygamous family groups
-eusocial systems - monogamous family groups
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-reproductive pair and nonreproductive individuals
-Canids, Primates, Cetaceans - polygamous family groups
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-polygynous
-vigilant male and harem of females
-Papio (baboons), Alouatta (howler monkey), lions - eusocial systems
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-queen - single reproductive female
-castes - sterile
-Heterocephalus glaberi - Heterocephalus glaberi
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-occur in colonies up to 40 individuals
-castes determined by max body size
-smallest = frequent workers, 25-30 g, do majority of burrowing and foraging
-larger = infrequent workers, 35 g, little burrowing, forage for selves
-largest = nonworkers, 40-45 g, bo burrowing or foraging, do parental care - costs of gregariousness
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-conspicuous
-increased intraspecific competition for resources and mates
-increased risk of parasitism and disease
-increased risk of inbreeding and inbreeding depression - benefits of gregariousness
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-selfish herd phenomenon - individual risk of predation low
-cooperative predator defense possible (e.g. Ovibos muschatus, ring around young)
-cooperative hunting possible
-information sharing (cultural inheritance)
-division of labor - what does the difference in costs among gender to gamete production explain?
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-polygyny more common than polyandry
-mate choice usually driven by female
-sexual selection more manifest in males (dimorphism, antlers, etc)
-philopatric dispersal - offspring tend to reproduce in same place as born
-males tend to be dispersers - direct fitness and indirect fitness
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-direct - benefits optimize survival of genes via direct descendants
-indirect - optimize fitness via relatives (non-direct descendants)
-direct + indirect= inclusive fitness - spermophilus beldingi
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-females tend to be philopatric (related to other females in colony)
-males tend to be unrelated
-thus, females give more alarm calling
-females implanted into other colonies don't engage in alarm calling - how does s. beldingi tell relatedness?
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-MHC loci - genes governing immune response, selection favoring variation
-odor of breakdown products of MHC loci in urine may help them tell relatedness - most common social system in carnivorans
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-asocial
-thought to be primitive
-ex. Ursids
-social behavior has evolved independently in some members of other families - examples of sociality in canids
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-Canis lupus - packs
-Vulpes vulpes - breeding pairs
-Canis latrans - resource dependent social behavior - social behavior in felids
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-lion - prides up to 4 breeding females and several nonbreeding females, one or more breeding males may or may not be related
-group hunting = division of labor
-satellite males = no pride, sneak copulations - social behavior in Hyaenids
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-crocutta crocutta - spotted hyena
-large groups (10-12 animals)
-cooperative defense of kills from lions - social behavior in mustelids
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-Meles meles - European badger
-communities of dozens of individuals
-sett - burrow system with multiple generations (clan or family group)
-benefits by having cooperative defense of territories from other clans - social behavior in 2 herpestids
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-Helogale - dwarf mongoose
-complex social system
-single breeding pair, phermonal suppression of non-breeding individuals
-forage independently
-cooperative predator defense and rearing of young
-also Suricatta (meerkat) - resource dispersion hypothesis
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-explains group living in carnivores - D.W. McDonald
-common set of starting conditions
--basic territoriality, individuals defend smallest patch of territory that can sustain them in bad year
--size depends on how resources are dispersed, usually patchy
-most of the time, years aren't bad and territory can sustain more than single individual
-most of time, selection favors group living - intrinsic factors of population regulation and cycles
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-aspects of life history of species
--birth rate
---age at first reproduction, average litter size, frequency of reproduction
--mortality rate
---species longevity, senescence - life past reproduction - extrinsic factors of population regulation
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-interactions between species of interest and other species/environment
--predation and competition
--interactions with pathogens
--food supply
--abiotic factors (climate, weather)
-can be stabilizing or destabilizing - ecxamples of species with dramatic population fluctuations that are very regular
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-Clethrionomys ruficamus
-Dicrostonys
-Microtus
-Lepus americanus
-Lynx rufus - arvicolinae
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-population cycles
-peaks may be 1-2 orders of magnitude higher than trough populations
-20,000 per ha in some peak
-1,000 per ha in trough
-very rapid growth rate
-crash cataclysmic
-lag period of 3-5 years between peaks - latitudinal component to arvicoline population cycles
- lower latitudes - decreased tendency to cycle
- two types of data for popuilation and conservation genetics
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-allozyme data
-DNA-based techniques - allozyme data
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-allelic forms of enzymes
-different ionic charges
-detect genetic variation
-inexpensive, can survey large number of loci - three types of DNA-based techniques
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-mtDNA
-nuclear DNA
-DNA-fingerprint loci - mtDNA
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-high evolutionary rate
-tends to be variable within species
-maternally inherited - nuclear DNA
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-sequence
-evolves more slowly than mtDNA
-microsatellite loci - AC repeat units
-biparentally inherited - DNA-fingerprint loci
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-assign paternity
-identify individuals - genetic testing used to assess what 6 things?
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-population differentiation
-gene flow
-hybridization
-determining mating system
-intraspecific phylogeny
-assessment of genetic diversity - ovis gmelini
- -microsatellite of 6 loci used to determine population differentiation
- gene flow
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-prevent population differentiationi
-SREC - white-tailed deer split into separate management units
-used separate allozyme data to evaluation gene flow between management units - hybridization in chipmunks
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-Tamis rudicaudus (mesic) and Tamias amoenus (xeric)
-subspp. Tamias amoenus canicaudus
-species can be distinguished by bacula bone
-ancient hybridization between T. amoenus and T. ruficaudus to create hybrid T. amoenus canicaudus - determining mating system
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-Pronghorn
-1-day estrus
-evaluated 25 pairs of twins
-44% had different fathers - intraspecific phylogeny
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-phylogeography - historical analysis of genetic variation
-worked with Sciurus aberti - Sciurus aberti
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-lives in ponderosa pines in the SW U.S.
-pines restricted to high elevation, thus, the squirrels are too
-squirrels located in isolated spots in SW U.S.
-historically, during Pleistocene cold periods, pine forests located lower down for more continuous population, then glaciers retreated
-predict what subspecific phylogeny should look like - problem with sciurus aberti hypothesis
- -study suggested east-west distribution inferring isolation before glaciation event
- assessment of genetic diversity
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-study of rare and endangered species
-Index using heterozygosity (H)
--individual basis (HI)
---avg number of loci at which individual is H
--population level (HP)
---H of avg individual in population - which index for assessing genetic diversity is more typically used
- -HP
- bottleneck
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-decrease in population size
-loss of genetic diversity
-2 causes - sampling error or inbreeding
-ex. Mirounga angustrirostris and Acynonyx and Cynomys gunnisoni - Mirounga angustirostris
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-northern elephant seal
-1800s - sailors hunted to near extinction, as few as 30 animals surviving
-current populations subject to allozyme studies
-Hp extremely low
-M. leonid, typical Hp = 4% - Acynonyx
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-cheetah
-10,000 years ago,non-anthropogenic bottleneck
-no genetic variation in cheetahs as measured by 155 allozyme loci
-unrelated individuals accept skin grafts from each other (MHC loci)
-can detect non-zero heterozygosity at microsatellites - Cynomys gunnisoni
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-all experience periodic plagues, wipe out 97% of populations
-periodic series of bottlenecks
-no variation in DNA fingerprints - examples of rare/endagnreded species that do not exhibit low diversity
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-Trichechus - normal levels of diversity
-Rhinocerus unicornus - same
--may be very early in bottleneck - significance of low diversity
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-diversity intimately linked to population viability
-Threats:
--1) increased susceptibility to disease and parasitism
--2) inbreeding depression
--3) decreased evolutionary potential - examples of increase in susceptibility to disease and parasitism for low diversity
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-cheetahs - virus FIP led to 50% mortality (normally, viruses lead to 1% mortality)
-Gunnison's prairie dogs and their susceptibility to plagues - inbreeding depression
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-decrease in fitness associated with high degree of inbreeding
--decreased sperm viability
--fluxuating asymmetry
--decreased growth rates
--lower survivorship to adulthood
--breakdown in social structure - Indian lions
- -high rate of sperm deformation
- decreased evolutionary potential
- -decreased ability to respond to future climatic variations
- criticisms of the thoery that there is an intimate link between population viability and genetic diversity
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1) low levels of variation may be fine
2) inbreeding depression rare in natural populations
3) inbreeding can increase population's ability to adapt
4) during bottleneck, allels lost are almost always low-frequency alleles
5) Genetic threats may be trivial - examples of animal that inbreed without inbreeding depression
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-Panthera tigris
-Speothos
-Leontopithecus rosalia - how can inbreeding increase population's ability to adapt?
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-increase fitness in long run
-1) increase in variation at polygenic traits (governed by more than 1 gene)
2) Genetic load - genetic load
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-cumulative effect of deleterious recessive alleles
-many deleterious alleles are recessive, hidden from selection in heterozygote
-in inbred population, heterozygosity is low, so recessive alleles not expressed as much
-inbreeding can purge these allels from population - genetic threats may be trivial
- -cheetah - habitat loss much more threatening
- ectothermy
- -body temperature and metabolic rate are proportional to ambient temperature
- lower critical temperature
- -highest ambient temperature at which endotherm expends energy to stay warm
- upper critical temperature
- -lowest ambient temperature at whicih endotherm expends energy to stay cool
- adaptations to cold
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-large size
-high BMR
-insulation
-Regional heterothermy
-Systemic heterothermy - adaptations to heat
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-avoid exposure
-low BMR
-evaporative cooling - avoiding exposure to heat
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-most heat-adapted mammals are nocturnal
-fossorial - burrows may be 35 degrees cooler than surface temps
-seasonal or daily dormancy (estivation - long-term in summer) - evaporative cooling
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-production of sweat
-panting (cooling in lungs, evaporation of saliva)
-application of saliva (ex. Macropodids and Cervids) - what's wrong with evaporative cooling?
- -places stres son water budgets, esp. in deserts
- strategies for water conservation
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-nocturnality
-fossorial
-nasal recycling
-production of concentrated urine - systemic heterothermy
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-adaptive hypothermia
-allow core body temp to drop, typically accompanied by dormancy
-results in enormous energy savings
-requires maintenance of thermogenic (brown) fat - systemic heterothermy characterized by
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-decrease in heart rate
-regional heterothermy
-decreased respiration rate
-decreased oxygen consumption and BMR
-decrease in body temp - dramatic energy savings for systemic heterothermy
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-very dramatic in small mammals in cold environments
-permits cold habitation by small mammals - thermogenic fat
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-highly vascularized
-high mitochondrial index
-metabolism of this fat produces heat
--stimulates arousal from adaptive hypothermia
COSTS:
1) mammals must invest energy in maintaining fat
2) Stores of this fat are limited - classification of adaptive hypothermia
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1) DEPTH - shallow (torpor) or deep (hibernation)
-shallow - slight derease in body temp
2) DURATION - seasonal or dailty
-seasonal AH tends to be deep
-induced by food limitation, photoperid
-may require prepatory period
-daily - shallow, circadian rhythms