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27 Cards in this Set
- Front
- Back
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What does each sex have to provide to produce offspring?
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Females
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Numerical Sex Ratio
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The ratio of the number of males to the number of females in the population
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Operational Sex Ratio
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The ratio of the number of males to the number of females in the population who are available for reproduction
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discuss The ratio of the number of males to the number of females in the population who are available for reproduction
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Remove males for: pre puberty, sterile,age
remove femoles for: post menopause, pregnat, lactating leaves many mare operational males then females |
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reproductive “bank balance
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Females:
Expend lots of time and metabolic energy in reproduction Greatly decreased numbers of females available for mating Males Expend little time and metablolic energy in reproduction Lesser decrease in numbers of males available for mating |
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Discuss conflicting strategies between males and females
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Females should be very choosy in mate choice
Males should mate with as many females as possible |
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How do females control reproductive investment by males?
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Imagine a male that does ‘something extra’ to enhance the survival of eggs he fertilized
If the ‘something extra’ reduces the investment by the female, more offspring should be able to be produced More offspring (male) are produced that carry the trait for providing ‘something extra’ and the trait spreads in the population |
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Males can demonstrate their willingness to ease the reproductive burden of females in two ways
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. Offer evidence of genetic quality
Offer some resource |
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How does courtship indicate genetic quality?
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Male needs to be healthy
Male has survived costs associated with courting - competition from other males - increased predator pressure |
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How does competing with males indicate genetic quality?
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Strongest (and presumably most fit) males win such fights
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1. What resources do males have to offer?
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territory
provides female with food and nesting sites costs the male time,energy, predation |
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2.What resources do males have to offer?
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food
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3. What resources do males have to offer?
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Other nutrient
spermatophore |
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4. What resources do males have to offer?
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parental care
extreme cases role reversal |
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What is Biodiversity?
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the entire array of biological variety contained in genes, populations, communities, and ecosystems
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what is genetic diversity?
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genetic variation within species
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what is species diversity?
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all the species on earth
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what is community diversity?
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The different biological communities and their associations with the physical environment (= ecosystem)
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What is habitat diversity?
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the various biomes of the earth, each comprised of many ecosystems
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What are Latitudinal Gradients in Biodiversity?
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Species diversity increases along a gradient from the poles to the equator
i.e. more species at equator |
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Why more species in the tropics?
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warmer climates
greater habitat variety higher productivity (= more food) higher stability (= older) |
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What are the threats to biodiversity? Habitat loss
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-85% of species effected by habitat loss
-habitat loss-actual destruction of habitat with little or no chance of recovery -habitat fragmentation-chopping habitat into parcels, with few or no corridors between each parcel(highway through a habitat) |
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What are the threats to biodiversity? habitat degradation
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the alteration of habitat - becomes temporarily unsuitable
(oil spills) |
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What are threats to biodiversity?
alien species |
introduction or invcasion of new species 49%
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other threats to biodiversity?
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pollution.disease,over exploitation
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What is the VALUE of Biodiversity?
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1. Instrumental Value - valuable to the economy
2. Intrinsic Value - valuable as itself 3. Future Value - future benefits (i.e. new medicines) |
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But HOW do we conserve biodiversity?
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We could protect KEYSTONE SPECIES
We could protect areas with the largest number of species We could protect KEYSTONE RESOURCES=resources that are critical to many species and to protect spaces |
