BIOL 241 Reproduction Lecture Slides PDF

Instructor: Dr. Sam Yeaman My research aims to understand how organisms adapt to their environment. Is evolution flexible? Do different species respond similarly/differently to the same challenge? Office hours: Wednesdays 4-5pm BI 394 [email protected] (subject: BIOL 241) Instructor: Dr....

Instructor: Dr. Sam Yeaman My research aims to understand how organisms adapt to their environment. Is evolution flexible? Do different species respond similarly/differently to the same challenge? Office hours: Wednesdays 4-5pm BI 394 [email protected] (subject: BIOL 241) Instructor: Dr. Sam Yeaman 100 80 We use computer simulations, genome sequence data, and statistical modelling H.annuus 60 40 20 0 100 80 H.argophyllus 60 40 Top candidate index (log10) 20 0 100 80 H.pet.fallax 60 40 20 0 Focal = H.annuus 100 Distance along chromosome (Mbp) Focal = other H.argophyllus H.pet.fallax 80 H.pet.petiolaris H.pet.petiolaris 60 Office hours: Wednesdays 4-5pm BI 394 40 20 [email protected] (subject: BIOL 241) 0  Upcoming this week and next Lecture Assignment 4 – Next Wednesday November 27 – Topic 10: Reproduction – Bring a response form! – D2L Content -> Lecture Assignments Overview of Biology 241 Biology 241 deals with energy flow in biological systems: Unit 1: Molecular Energy Transformations Unit 2: Cellular Energy Transformations Unit 3: Energy Allocation in Organisms A. Energy Budgets B. Thermoregulation C. Locomotion D. Reproduction Unit 4: Energy Flow in Ecosystems Chapter 26, sections 26.1 to 26.4, 26.7b  Learning Objectives: 1. Explain why energy is needed for growth (e.g., synthesis of new tissues, repair and reproduction) 2. Define “life history”; explain how and why life history strategies vary among species and even within populations. Recognize how life history traits co-vary across species, often along a continuum associated with r and K selection strategies 3. Be able to interpret life tables and survivorship curves; describe the three types of survivorship curves and provide an example of an organism exhibiting each type of curve 4. Explain what is meant by a life-history tradeoff: interpret data in terms of costs/benefits and tradeoffs between current reproduction and other uses of energy. Recognize that the optimal resolution of these tradeoffs determine life history traits such as: when to start breeding, how often to breed, how much to invest in each offspring, and how long to live  Eproduction The ideal: unlimited resources to support maximal growth, long life continuous production of offspring (with high survival) Most organisms do not live under these conditions Energy must be spent to find food, avoid predators, etc. – Ultimate goal of managing an energy budget properly is to have energy remaining to allocate to reproduction Natural selection has resulted in numerous strategies (called life history traits ) to maximize lifetime reproductive success (FITNESS)  Life History Theory Every species has a pattern of growth and development, reproduction, and death shaped by natural selection success in the past shapes the life history traits of a species The environment affects life history traits by influencing energy budgets: amount of light, food sources, shelter, wind, precipitation, etc. Maximizing reproductive success involves trade-offs due to fixed energy budgets and selective pressures (environment)  Trade-offs arise from limits in energy budgets If 2 life-history traits compete for a share of limited resources, then it's impossible to maximize both traits simultaneously – any gains by one trait will result in a loss by the other Example: seed size vs seed number Number of seeds Fitness Fitness Number of seeds Seed size Seed size  Growth Indeterminate Growth Growth of the organism continues throughout the lifespan (example: ectotherms - reptiles, fish, plants, etc) Determinate Growth  Growth Indeterminate Growth Growth of the organism continues throughout the lifespan (example: ectotherms - reptiles, fish, plants, etc) Determinate Growth Growth of the organism ceases when “adult” state is reached (example: endotherms - birds, mammals)  Reproduction Asexual reproduction produces clones (“exact” copy) – Prokaryotes replicate their genome and then divide by binary fission – Some eukaryotes replicate their genomes and divide by mitosis (protists, fungi, some plants) Sexual reproduction produces recombinants – –  Reproduction Asexual reproduction produces clones (“exact” copy) – Prokaryotes replicate their genome and then divide by binary fission – Some eukaryotes replicate their genomes and divide by mitosis (protists, fungi, some plants) Sexual reproduction produces recombinants (combined genomes) – Replicated genomes are halved into gametes (sperm or eggs) and combined with other gametes to produce a zygote – Only in eukaryotes  Life History Traits Life history traits are variable: – Growth rate – Parental investment – Number of offspring (fecundity) – Frequency of reproduction (parity) – Size/age at sexual maturity – Size of offspring – Longevity/life expectancy (mortality rate) Tradeoff Between Growth Rate and Reproduction en.wikipedia.org/wiki/File:Blue- headed_wrasse_det.jpg Blue-headed wrasse (Thalassoma bifasciatum) -Warner (1984; Evolution 38:148)  Growth & reproduction in white suckers Indeterminate growth Growth slows at maturity 3-5 y 3-5 y Data from Ontario lakes Beamish, R.J. 1973. J. Fish. Res. Board Can. 30:607-616 How Much Parental Investment Should a Parent Provide Each Offspring? How Many Offspring Should Be Produced? Passive care = pre “birth” energy investment (seed development, gestation, etc.) Active care = post “birth” energy investment (raising offspring) Orchid seeds Mice Coco-de-mer seed Elephants All images Wikimedia Commons How Much Parental Investment Should a Parent Provide Each Offspring? How Many Offspring Should Be Produced? Passive care = pre “birth” energy investment (seed development, gestation, etc.) Active care = post “birth” energy investment (raising offspring) Orchid seeds Mice little passive care no active care lots of seeds, some survive Coco-de-mer seed Elephants lots of passive care no active care one large seed (high energy store to increase survival) All images Wikimedia Commons How Much Parental Investment Should a Parent Provide Each Offspring? How Many Offspring Should Be Produced? Passive care = pre “birth” energy investment (seed development, gestation, etc.) Active care = post “birth” energy investment (raising offspring) Orchid seeds Mice little passive care some passive care (few weeks) no active care some active care lots of seeds, some survive multiple offspring, some live Coco-de-mer seed Elephants lots of passive care high passive care (18 mos) no active care high active care (4 years) one large seed few offspring (high energy store to increase survival) All images Wikimedia Commons Each point on the following graphs relates the average number of eggs in a reproductive season to the average number of reproductive seasons. Each point is a species. Which graph describes a trade-off between egg number and number of reproductive seasons? A B C Egg number Egg number Egg number Reproductive Seasons Reproductive Seasons Reproductive Seasons  A Trade-off Between Parental Care and Survival of Offspring European Magpie (Pica pica) average ~7 eggs per clutch results in 3-4 fledged (ready to fly) Wikimedia Commons always some lost to disease/predation (same with lower clutch size) less energy to go around (parents couldn’t feed them all) 9 eggs a total loss (very little energy) -Hogstedt (1980; Science 4474:1148)  A Tradeoff Between Reproduction and Survival of Parent Not enough energy for both high fecundity and high survivorship Wikimedia Commons species with low fecundity and low survivorship go extinct n = 118 species Ghalambor & Martin. 2001. Science 292:494- 497 Recap of Monday’s lecture: The critical factor we discussed was that energy budgets are limited. Organisms can only take in so much food/light, and with that limited supply, they must "decide" how to spend it. If they spend more energy on laying lots of eggs, they will have less energy left over to run away from predators, and may suffer mortality. On the other hand, if they spend less energy on laying eggs and only run around and avoid getting caught, they'll live a long life but leave few descendents. Natural selection favours whatever strategy leaves the most descendents. Thus: over time, it favours whatever particular combination of traits is best suited to the environment. Because species live in different environments, they tend to differ in their life history strategies and combinations of life history traits that work best.  A Tradeoff Between Reproduction and Survival of Parent Mortality rates of female red deer (Cervus elaphus) = with fawns = no fawns Wikimedia Commons =female No offspring = energy to sustain self (until old age) Reproduction is costly in the young (not done developing) and old (can’t maintain self) -Clutton-Brock et al. (1982; Red deer: Behavior & ecology of two sexes; pg. 77) Based on this figure: A. Reproductive females are protected from disease B. Non-reproductive females don’t die C. Reproduction in red deer increases mortality rate D. Bambi’s mom wasn’t going to make it anyway  How Often Should an Individual Reproduce? west/britishcolumbia-south/britishcolumbia-south.html Parity = how often an individual reproduces www.salmonatlas.com/pacific-salmon/canada- Semelparity Individuals of the same species can breed only once in its lifetime e.g., a Pacific salmon: long trip from ocean to spawning stream - breed and die Iteroparity: www.salmonatlas.com/atlanticsalmon/canada- Individuals of the same species can breed more than once in its lifetime e.g., Atlantic salmon: short trip from ocean to east/labrador/labrador.html spawning stream - return to ocean after breeding  Does Evolution Favour Larger Organisms? Drosophila melanogaster Fecundity (ability to make many offspring) increases with body size Large female - advantage to delaying sexual maturity until larger Small female Roff (1981; American Naturalist 118:405) A Tradeoff Between Mating and Lifespan Female Fruit Flies (Drosophila) A = normal & mated B = no ovaries (no eggs) C = virgins D = mated, but sterilized Females that laid eggs had shorter lifespans Maynard Smith (1958; Journal of Experimental Biology 35:832-842) A Tradeoff Between Mating and Lifespan Male Fruit Flies (Drosophila) housed Inseminated ♀ won't with mate with males ♀ males housed with virgin females reproduce and have shorter lifespans housed Also larger males live longer ♂ with ♀ -Partridge & Farquhar (1981; Nature 294:580)  Predation affects life history traits Example of an environment affecting life history traits: Trinidadian guppies and predation Guppies Predator – pike cichlids http://animaldiversity.org higher pond elevation fewer predators larger guppy size at reproduction http://labs.eeb.utoronto.ca/rodd/images/patternvariation.jpg lower pond elevation more predators smaller guppy size at reproduction  Predation affects life history traits Example of an environment affecting life history traits: Trinidadian guppies and predation Size at reproduction (mm) High Med. Low High Med. Low Predation Level  Nematode (C. elegans) How Long to Live? commons.wikimedia.org/wiki/File:Caenorhabditis_elegans.jpg -Kenyon et al. (1993; Nature 366:461)  Why not live forever? In the same environment, introduce nematodes (half wild type, half daf-2 mutants). Follow the frequency of daf-2 allele over time (generations) -Jenkins et al. (2004; Proceedings of the Royal Society B 271:2523) A human, Bob, has 3 children over the course of 6 years. Bob’s sister, Jane, only has one child. Based on this information Jane would be considered: A. Semelparous B. Iteroparous C. Heterolithoparous D. Lonely  Life History Strategies Form a Continuum r-Selected K-Selected (r-Strategists) (K-Strategists) K-Selected Species r-Selected Species Small offspring/adult size Large offspring/adult size Early sexual maturity Late sexual maturity Semelparous Iteroparous High fecundity (lots of offspring) Low fecundity (few offspring) Low parental investment High parental investment Low juvenile survivorship High juvenile survivorship Short lifespan Long lifespan Evolved to reproduce quickly Evolved to compete  Life History Tables - How do we know if r or K? Summarize information on age structure, size, life-history (reproductive) stage, and survivorship of a population Used to predict how a population will change over time Useful in managing: Crops and livestock (farming planning) Conservation efforts (captive breeding programs) Pest/weed control etc…  Age Structure Pyramids Snapshot of a particular point in time F 29.23a Age Structure Pyramids: Example  Life History Tables Follow a particular cohort through time x (years) nx sx lx mx lx mx 0 72 0.375 1.0 0 0 1 27 0.667 0.375 1.8 0.675 2 18 0.278 0.250 2.1 0.525 3 5 0.800 0.069 1.8 0.124 4 4 0.750 0.056 5 0.280 5 3 0.667 0.042 4 0.168 6 2 0 0.028 0 0 7 0 - 0 0 0 R0 1.772 Data from: Smith (1988; in Lifetime Reproductive Success; Clutton-Brock (ed.)) x – age nx – # of females at each age (x) in your cohort sx – survival rate from one age to the next lx – survivorship (fraction of original cohort still alive) mx – fecundity (avg. # female offspring each living female produces) (values will be provided) R0 – net reproductive rate (avg. # female offspring per female in cohort over the cohort’s lifespan)  Life History Tables l x = nx Follow a particular cohort through time n0 x (years) nx sx lx mx lx mx l1 = 27/72 0 72 0.375 1.0 0 0 1 27 0.667 0.375 1.8 0.675 = 0.375 2 18 0.278 0.250 2.1 0.525 3 5 0.800 0.069 1.8 0.124 l4 = 4/72 4 4 0.750 0.056 5 0.280 = 0.056 5 3 0.667 0.042 4 0.168 6 2 0 0.028 0 0 7 0 - 0 0 0 R0 1.772 Data from: Smith (1988; in Lifetime Reproductive Success; Clutton-Brock (ed.)) x – age nx – # of females at each age (x) in your cohort sx – survival rate from one age to the next lx – survivorship (fraction of original cohort still alive) mx – fecundity (avg. # female offspring each living female produces) (values will be provided) R0 – net reproductive rate (avg. # female offspring per female in cohort over the cohort’s lifespan)  Life History Tables l x = nx Follow a particular cohort through time n0 x (years) nx sx lx mx lx mx l1 = 27/72 0 72 0.375 1.0 0 0 1 27 0.667 0.375 1.8 0.675 = 0.375 2 18 0.278 0.250 2.1 0.525 3 5 0.800 0.069 1.8 0.124 l4 = 4/72 4 4 0.750 0.056 5 0.280 = 0.056 5 3 0.667 0.042 4 0.168 6 2 0 0.028 0 0 7 0 - 0 0 0 R0 1.772 Data from: Smith (1988; in Lifetime Reproductive Success; Clutton-Brock (ed.)) x – age nx – # of females at each age (x) in your cohort sx – survival rate from one age to the next lx – survivorship (fraction of original cohort still alive) mx – fecundity (avg. # female offspring each living female produces) (values will be provided) R0 – net reproductive rate (avg. # female offspring per female in cohort over the cohort’s lifespan)  sx = nx+1 Life History Tables l x = nx nx Follow a particular cohort through time n0 x (years) nx sx lx mx lx mx s0 = 27/72 l1 = 27/72 0 72 0.375 1.0 0 0 = 0.375 1 27 0.667 0.375 1.8 0.675 = 0.375 2 18 0.278 0.250 2.1 0.525 s1 = 18/27 3 5 0.800 0.069 1.8 0.124 l4 = 4/72 = 0.667 4 4 0.750 0.056 5 0.280 = 0.056 5 3 0.667 0.042 4 0.168 6 2 0 0.028 0 0 7 0 - 0 0 0 R0 1.772 Data from: Smith (1988; in Lifetime Reproductive Success; Clutton-Brock (ed.)) x – age nx – # of females at each age (x) in your cohort sx – survival rate from one age to the next lx – survivorship (fraction of original cohort still alive) mx – fecundity (avg. # female offspring each living female produces) (values will be provided) R0 – net reproductive rate (avg. # female offspring per female in cohort over the cohort’s lifespan)  sx = nx+1 Life History Tables l x = nx nx Follow a particular cohort through time n0 x (years) nx sx lx mx lx mx s0 = 27/72 l1 = 27/72 0 72 0.375 1.0 0 0 = 0.375 1 27 0.667 0.375 1.8 0.675 = 0.375 2 18 0.278 0.250 2.1 0.525 s1 = 18/27 3 5 0.800 0.069 1.8 0.124 l4 = 4/72 = 0.667 4 4 0.750 0.056 5 0.280 = 0.056 5 3 0.667 0.042 4 0.168 6 2 0 0.028 0 0 7 0 - 0 0 0 R0 1.772 Data from: Smith (1988; in Lifetime Reproductive Success; Clutton-Brock (ed.)) x – age nx – # of females at each age (x) in your cohort sx – survival rate from one age to the next lx – survivorship (fraction of original cohort still alive) mx – fecundity (avg. # female offspring each living female produces) (values will be provided) R0 – net reproductive rate (avg. # female offspring per female in cohort over the cohort’s lifespan)  sx = nx+1 Life History Tables l x = nx nx Follow a particular cohort through time n0 x (years) nx sx lx mx lx mx s0 = 27/72 l1 = 27/72 0 72 0.375 1.0 0 0 = 0.375 1 27 0.667 0.375 1.8 0.675 = 0.375 2 18 0.278 0.250 2.1 0.525 s1 = 18/27 3 5 0.800 0.069 1.8 0.124 l4 = 4/72 = 0.667 4 4 0.750 0.056 5 0.280 = 0.056 5 3 0.667 0.042 4 0.168 6 2 0 0.028 0 0 7 0 - 0 0 0 R0 1.772 Data from: Smith (1988; in Lifetime Reproductive Success; Clutton-Brock (ed.)) x – age nx – # of females at each age (x) in your cohort sx – survival rate from one age to the next R 0 = Σ(l x *mx ) lx – survivorship (fraction of original cohort still alive) mx – fecundity (avg. # female offspring each living female produces) (values will be provided) R0 – net reproductive rate (avg. # female offspring per female in cohort over the cohort’s lifespan)  sx = nx+1 Life History Tables l x = nx nx Follow a particular cohort through time n0 x (years) nx sx lx mx lx mx s0 = 27/72 l1 = 27/72 0 72 0.375 1.0 0 0 = 0.375 1 27 0.667 0.375 1.8 0.675 = 0.375 2 18 0.278 0.250 2.1 0.525 s1 = 18/27 3 5 0.800 0.069 1.8 0.124 l4 = 4/72 = 0.667 4 4 0.750 0.056 5 0.280 = 0.056 5 3 0.667 0.042 4 0.168 6 2 0 0.028 0 0 7 0 - 0 0 0 R0 1.772 Data from: Smith (1988; in Lifetime Reproductive Success; Clutton-Brock (ed.)) x – age nx – # of females at each age (x) in your cohort sx – survival rate from one age to the next R 0 = Σ(l x *mx ) lx – survivorship (fraction of original cohort still alive) mx – fecundity (avg. # female offspring each living female produces) (values will be provided) R0 – net reproductive rate (avg. # female offspring per female in cohort over the cohort’s lifespan) If R0 < 1, population is decreasing; if R0 > 1, pop is increasing; if R0 = 1, stable What is the survival rate (sx) at year 1 (s1)? A. 100% (1.0) x (years) nx 0 20 B. 75% (0.75) 1 15 2 5 C. 67% (0.67) 3 0 D. 33% (0.33) E. 25% (0.25)  The population size for this species is: x (months) nx sx lx mx lx mx 0 1187 0.55 1.00 0 0.00 1 653 0.40 0.55 0 0.00 2 261 0.18 0.22 2.2 0.484 3 47 0.00 0.04 13 0.52 4 0 - 0.00 0 0.00 R0 1.004 A. Increasing (getting larger) B. Remaining relatively stable (staying ~ the same size) C. Decreasing (getting smaller) D. Extinct  This population is: x (months) nx sx lx mx lx mx 0 1187 0.55 1.00 0 0.00 1 653 0.40 0.55 0 0.00 2 261 0.18 0.22 2.2 0.484 3 47 0.00 0.04 13 0.52 4 0 - 0.00 0 0.00 R0 1.004 A. Increasing (getting larger) B. Remaining relatively stable (staying ~ the same size) C. Decreasing (getting smaller) D. Extinct  Life History Tables Survival rate Survivorship (sx) (lx) Table 26.1  Survivorship Curves (made from life history tables) LOG scale F 29.7 Type I Type II Type III Low mortality until end of life large animals, few young high parental care, high juvenile survivorship K-selected  Survivorship Curves (made from life history tables) LOG scale F 29.7 Type I Type II Type III Low mortality until end of life Constant rate of large animals, few young mortality throughout the high parental care, high lifespan juvenile survivorship mix of r & K traits K-selected  Survivorship Curves (made from life history tables) LOG scale F 29.7 Type I Type II Type III Low mortality until end of life Constant rate of low juvenile surviorship large animals, few young mortality throughout the Mortality rate decreases high parental care, high lifespan with age juvenile survivorship mix of r & K traits r-selected K-selected  How to Detect Constant Mortality (Type 2 survivorship) % Surviving 5% Log 25% 50% On linear scale, constant mortality looks like a Type 3 curve… On log (ln) scale, constant mortality looks like it should (Type 2) 50% = 50, 25, 12.5, 6.25 25% = 75, 56, 42 5% = 95, 90, 86  Patterns of Survivorship (from sparrow life history table) 80 "Melospiza melodia 01450t" by Walter Siegmund Number of individuals alive (nx) 60 40 Log (nx) 20 Age (y) 0 0 2 4 6 Age (years) Linear scale Log scale The mortality rate of organisms following a Type III Survivorship Curve is: A. Fairly constant throughout life B. Higher in post-reproductive years C. Lower as the organisms become older D. Unrelated to age  Learning Objectives: 1. Explain why energy is needed for growth (e.g., synthesis of new tissues, repair and reproduction) 2. Define “life history”; explain how and why life history strategies vary among species and even within populations. Recognize how life history traits co-vary across species, often along a continuum associated with r and K selection strategies 3. Be able to interpret life tables and survivorship curves; describe the three types of survivorship curves and provide an example of an organism exhibiting each type of curve 4. Explain what is meant by a life-history tradeoff: interpret data in terms of costs/benefits and tradeoffs between current reproduction and other uses of energy. Recognize that the optimal resolution of these tradeoffs determine life history traits such as: when to start breeding, how often to breed, how much to invest in each offspring, and how long to live