Week 4: Chapters 8-9
Week 4: Chapters 8-9 301
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This 6 page Class Notes was uploaded by Morgan Deal on Tuesday September 22, 2015. The Class Notes belongs to 301 at University of South Carolina taught by Dr. April South in Summer 2015. Since its upload, it has received 57 views. For similar materials see Ecology and Evolution in Biology at University of South Carolina.
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Date Created: 09/22/15
CHAPTER 8 Life Histories Life History Traits 0 Life history schedule of organism growth development reproduction and survival 0 Fecundity number of offspring produced per reproductive episode 0 Parity number of reproductive episodes experienced that produce viable o spnng 0 Parental investment time and energy given by parents to care for offspring o Longevity life expectancy Slow to Fast Continuum Slow Life History Fast Life History Long time to sexual maturity Short time to sexual maturity Long life span Short life span Low number of offspring High number of offspring High parental investment Low parental investment Allocation o Principle of allocation when resources are devoted to 1 body structure physiological function or behavior they can t be allotted to others 0 Leads to tradeoffs 0 Optimized life history meets demands of survival AND reproduction 0 Number of offspring vs size increase in offspring size leads to decreased fecundHy 0 Negative correlation between number and size 0 Selection favors uniform offspring size rather than offspring number 0 Number of offspring vs parental care if the number of offspring increases the amount of parental care each offspring receives decreases 0 Parental resources are spread more thinly due to increased fecundity 0 Parental care vs parental survival more care to offspring results in lower parental survival 0 Growth rate vs fitness 0 Determinate growth individual doesn t grow more once reproduction is initiated Occurs mostly in mammals and birds Long life span 0 Indeterminate growth individual continues growth after reproduction Short life span Semelparity and lteroparity o Semelparity organisms reproduce once 0 Mostly insects and plants 0 Can mate multiple times but reproduction only happens once 0 Lots of energy needed for reproduction lteroparity organism reproduces multiple times Annual organism lives for only 1 year Perennial life span is greater than 1 year Longevity life expectancy Stimuli Cause Change Photoperiod amount of light occurring each day Resource availability fluctuations influence life history events Predation hatching metamorphosis and sexual maturity affected Global warming changes in breeding times usually happens earlier 0 Other resources such as food may not respond to the same warming cues Altered breeding Humans can cause lower genetic variation decrease in organism size earlier sexual maturity Senescence Gradual decrease in fecundity and increase in probability of mortality Occurs in humans between ages 3085 Physiological functions decrease Organisms with longer life spans tend to have better repair mechanisms Stress Tolerators Competitors Ruderals Potential growth Slow Fast Fast Age of sexual Late Early Early maturity Energy needed to Low Low High make seeds Importance of Frequently Often Rarely vegetative reproduction CHAPTER 9 Reproductive Strategies Reproduction 0 Sexual reproduction progeny inherit DNA from 2 parents 0 Gonads primary sex organs 0 Diploid cells have random genes 0 Asexual reproduction DNA inherited from 1 parent 0 Produces clones most often 0 Vegetative reproduction offspring produced from nonsexual parent ssues Clones offspring with the same genotype as parents Binary fission duplication of genes followed by division of the cell 0 Parthenogenesis embryo produced without fertilization Clones germ cells directly become egg cells Genetically variable germ cells undergo partial or complete meiosis Most organisms produced are female Sexual Reproduction 0 Costs 0 Considerable use of Energy Resources 0 Increased risk of Herbivory flowers and fruits attract animals Predation Parasitism 0 Cost of meiosis 50 reduction in amount of parent s genes passed down to next generation 50 from each parent Counterhermaphroditism Counter both parents take care of offspring 0 Benefits 0 Purging mutations can lose bad mutations during meiosis Homozygous recessive genotypes are often unviable o Coping with environmental variation offspring may encounter beneficial variation from each parent 0 Coping with parasites and pathogens Red Queen Hypothesis Hosts rapidly evolve to counter evolution of parasites through sexual reproduction Sexual Strategies 0 Perfect flowers contain male and female parts 0 Simultaneous hermaphrodites have male and female reproductive functions at the same time 0 Can self fertilize o Sequential hermaphrodite alternates between male and female reproductive func ons Monoecious have separate male and female parts on the same individual Dioecious whole plant has either male or female parts Selffertilization selfing hermaphrodite breeds itself Outcrossing an organism breeds another Mixed mating strategies individuals can self OR outcross o Selfing is better than not mating at all Comparing Sexual Strategies Fitnees through male reproduction Fitness of hermaphrodite exceeds the fitness of a male or female Fifneeq H1 rnlmh Fitnee through male reproduction Fitness of hermaphrodite is less than the fitness of a male or female Fitneee through female reproduction Offspring Sex Ratios 0 Sex determination 0 Genetic inheritance of sexspecific chromosomes Presence or absence 0 Whether or not eggs are fertilized fertilized insects are female for example 0 Environmental sex determination environmental conditions determine sex 0 Temperature dependent sex determination 0 Female influence to ratio female determines which sex chromosome fertilizes or if the egg gets fertilized 0 Deer can abort male embryos depending on the availability of resources 0 Frequency dependent selection rare phenotypes favored due to better fitness 0 Cycle 0 Highly skewed sex ratios 0 Local mate competition mate competition in small space causes skewed sex ratio Mating System 0 Mating system number of mates each individual has and the permanence of the relationship 0 Promiscuity everyone mates with everyone 0 Polygamy 1 individual has long term relationships with multiple others 0 Polygyny 1 male multiple females Due to male competition 0 Polyandry one female multiple males Females looking for superior sperm or material benefits 0 Monogamy one male one female 0 Relationships last long enough to produce offspring o Males important to raising offspring o Extrapair copulation social bond with one mate but mating with other individuals as well 0 Open relationship 0 Causes more variation 0 Mate guarding preventing the other mate from extra pair copulation Sexual Selection 0 Sexual selection natural selection for sexspecific traits related to reproduction 0 Sexual dimorphism difference in phenotype between males and females of the same species 0 Primary sexual characteristics related to fertilization 0 Secondary sexual characteristics noticeable phenotypic differences such as size color etc Evolution of Female Choice 0 Increased fitness 0 Material benefits food shelter etc 0 Good genes hypothesis selecting males with better genotype 0 Good health hypothesis selecting males with the best health Evolution of Sexual Traits o Runaway sexual selection selection for trait is reinforced until no genetic variation remains o Handicap principle the higher the handicap the higher the ability to offset the trait o Honest signals signals that indicate phenotype o Dishonest signals will die out
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