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Home , Copulation (zoology), Internal fertilization, Reproduction, Reproductive success, Sexual reproduction

Reproductive &

REPRODUCTIVE ECOLOGY & SEXUAL SELECTION • Asexual • Sexual – Attraction, , and – Fertilization – Production of Young

The Evolutionary Enigma of Benefits of Asex • Sexual reproduction produces fewer reproductive than , a so-called reproductive handicap 1. Eliminate problem to locate, court, & retain suitable mate. Asexual reproduction Sexual reproduction Generation 1 2. Doubles growth rate. Female

3. Avoid “cost of ”: Generation 2 – genetic representation in later generations isn't reduced by half each time Male 4. Preserve pool adapted to local Generation 3 conditions.

Generation 4

Figure 23.16

The Energetic Costs of Sexual Reproduction Benefits of • Allocation of 1. Reinforcement of social 2. Variability in face of changing environment. – why buy four lottery tickets w/ the same number on them? Relative benefits: Support from both asexual in constant & sexual in changing environments – have wingless female clones & winged male & female dispersers – conjugate if environment is deteriorating

Heyer 1 Reproductive Ecology & Sexual Selection

Simultaneous TWO • Advantageous if limited mobility and dispersal and/or low population density • Guarantee that any member of your encountered is the • Conjugation “right” sex • Self fertilization still provides some – protozoans with + & - mating types. • Or prevent self-fertilization by • Monoecious: both sexes in one individual. § § producing sperm or • Dioecious: separate sexes at different times

– one sex makes small haploid (sperm) , , snails, – the other makes big ones (eggs)

8’ long from Ecuador Simultaneous sperm exchange

Sequential Hermaphrodites Determinate (fixed) Gender

• Protandry: when all else equal • Gametic determination – make sperm when small – Heterogenic male determination (XY male) • you still make more than needed – Heterogenic female determination (XY female) – make eggs when large – Haplotypic male determination (XO male) • costlier & bigger • Environmental determination • Protogyny: when all else isn’t equal – Temperature – especially if big individuals get more mates – Intrauterine position • be a big male: wrasses.

Determinate Gender, Biased Sex-ratios yet Biased Sex Ratios in Red Deer

Dominant does • Primary Sex Ratio: Ø Sex ratio at fertilization

Non-dominant does • Secondary Sex Ratio: Ø Sex ratio at • Tertiary Sex Ratio: Ø Sex ratio at sexual • ↑ frequency of male calves to dominant mothers – Dominant moms more likely to yield dominant bucks → ↑ odds of perpetuating maturity her • Quaternary Sex Ratio: – Δ ratio probably from pre-implantation events Ø Sex ratio of • ↓ frequency of male calves in poor conditions (E.g., ↑density) population – Males larger → more expensive to raise – Δ ratio probably from post-implantation events

Heyer 2 Reproductive Ecology & Sexual Selection

External Fertilization Broadcast Spawning

• Only in water • E.g. marine inverts - larval mortality is high. – gametes must be moist. • Release in response to: • release is – smell of other gametes synchronized. – environmental cues • Palolo Worm

Courtship Mate Attraction — Courtship

• Auditory • Chemical • • Visual • Colors • Bioluminescence •

Internal Fertilization Courtship Spawning • Terrestrial forms need so gametes don't dry out • In , , & some marine inverts • Decreases spent on sperm production • Ensure large amounts of your sperm are on target • Behaviors stimulate gamete release • Allow to store concentrated sperm • Produce fewer eggs but may add in • are – it’s a balance of investment strategy sperm packages – , squid. • Adpressed – lack intromittive organs

Heyer 3 Reproductive Ecology & Sexual Selection

Estrogens & Ovulation Copulatory Organs Ovulation triggered by a sharp rise in estrogens

• Legs – squids & spiders Insert fig. 20.35 • Claspers – & rays • – – turtles, — protrusable – lizards, w/ paired hemipenes — eversible Estrogen rise and female reproductive behavior – w/ bifurcated • Proceptive behavior: “flirting” — advertising sexual state – eutherian w/ penis & bacculum. • Receptive behavior: attentive to male courting • Conceptive behavior: accepting copulation

Oviparity: Laying • Yolk w/ & fats • Birds – Energetically very expensive! • Protective Coating – jelly-like substance in aquatic forms – earthworm's cocoon – horny egg case of some sharks – calcareous or leathery shell of birds &

Ovoviviparity: Retain Eggs Internally Continued • Nest guarding • Brooding • “Mobile nest” • allocation Dogfish “candle” from – Less energy spent on • Keeping eggs warmer female’s uterus egg production speeds development. – Use energy insuring development of fewer – Cold climate reptiles offspring retain eggs rather than – Often, females spend laying them. energy on egg production – Males do the parental care

“Candle” opened to show small with large yolk

Heyer 4 Reproductive Ecology & Sexual Selection

Viviparity: Maternal Nourishment : Maternal Nourishment • Maternal Nourishment • Maternal Nourishment – Spreads maternal energy demand over longer time period – Spreads maternal energy demand over longer time period – Allows to grow beyond original egg size – Allows embryo to grow beyond original egg size • Placenta connects embryo to mother for & • Aplacental viviparity: intra-uterine feeding. gas exchange. – “Uterine milk” – rays – Placental mammals – Oophagy (& adelphophagy!) – mackerel sharks – Reptiles (rattlesnakes Gill filaments for & sea snakes) absorbing uterine milk in river – Fish (sharks, , pup. (Later, will drink surf perch) by bucchal pumping.)

Swollen bellies of oophagous porbeagle shark pups

Aphids — a little bit of everything! Aphids — a little bit of everything! 1. .Asexual (parthenogenic) viviparity “ ” – And telescoping generations (born pregnant!) • yearly cycles 2. Seasonally alternating with a dioecious generation having: Sexual oviparity

• Parthenogenic live birth (all females) • And the baby being born already has a baby!

EVOLUTION OF “Survival of the fittest” • & Variability • Non-Adaptive • Adaptive Evolution: “Reproduction • Sexual Selection of the fittest”

Heyer 5 Reproductive Ecology & Sexual Selection

Sexual Selection Sexual Selection • Even though some variations may increase survival, health, competitive success, etc., … • Natural Selection (NS): differential • they will not increase in frequency in the gene reproduction due to differential survival. pool if they are not also associated with increased ! • Sexual Selection (SS): differential reproduction due to increased Reproductive • Even though some variations may decrease Success (RS) despite possible decreased survival, health, competitive success, etc., … survival. • they will increase in frequency in the gene pool if they are also associated with increased reproductive success!

Sexual Selection and the Sexual Selection Energetic Costs of Reproductive Success • Increased Reproductive Success comes at increased energetic costs → decreased survival

Mating calling in the most energetically expensive activity in their . • Aerobic up 25x for several hours • Sexual Selection: differential reproduction due to 1. Advertising calls (chorus) increased Reproductive Success despite possible 2. Aggressive calls decreased survival. 3. Courtship calls (solo) – Louder vocalizations → stronger attraction for mates

– Louder vocalizations → stronger attraction for predators!

Social Sex Sexual Selection • Promiscuous • No social bonding • Observed – sexes differ in size, color, or behavior • Monogamous • One female + one male • Some differences don’t aid survival – dimorphic feature makes more obvious • Polygamous (sexually dimorphic) – Polygynous • One male + multiple females – Polyandrous • One female + multiple males

Heyer 6 Reproductive Ecology & Sexual Selection

Sexual Selection Sexual Selection • Game Theory (rock-paper-scissors) • Frequency-dependent • Intrasexual Selection: Intrasexual Selection: – competition among members of one sex for – Oscillating frequencies access to members of the other sex. • Side-blotch lizard – Orange-spotted males – a.k.a. Male-Male Competition. • Aggressive, large harems – Blue-spotted males • Less-aggressive, small harems DISPLACES – Yellow-spotted males • Non-aggressive, no harems

DISPLACES DISPLACES

Sexual Selection Female Choice

• Intrasexual Selection • Intersexual Selection: – ability of one sex to woo the opposite sex. – a.k.a. Female Choice.

Female Choice in New Guinea Female Choice Birds of Paradise & Hills Tribes • Bowerbirds: display is separate from .

https://www.youtube.com/watch?v=KIYkpwyKEhY https://www.youtube.com/watch?v=DU-V3OYwwQU

Heyer 7 Reproductive Ecology & Sexual Selection

Social & Why Females Choose and Males Fight: Parental Investment & Sexual Selection • Sex w/ most invested has most to loose:

• Female introduced to – Eggs more “expensive” than sperm unaccompanied males – Females must be selective Ø Choose most brightly ornated • Female guppy introduced to one • Female RS limited by # of young they raise. accompanied male + unaccompanied males • Male RS limited by # of females they mate. Ø Choose whichever color-pattern the accompanied male has

Reversed Dimorphism Monogamy Where the female is the pursuer because she invests less. ~1% of bird spp • Phalarope females are bigger and brighter. Social monogamy Polygyny ~90% of bird spp ~2% of bird spp

Polyandry <1% of bird spp

male female • Females lay a clutch every 10-12 days ~6% of bird spp • Male clutch care takes 3 months • Females will destroy eggs to free up a male Ala male , primates, mice

Paternal brood care vs. resource supply Speaking of in species of Eurasian warblers the Birds and the … ↓food → ↑care/↑monogamy

↑food → ↓care/↑promiscuity

• Super polyandry / abbreviated promiscuity r = -0.859, P < 0.0001 • Sperm competition https://www.theguardian.com/environment/video/2013/sep/06/queen--wedding-flight-video

Heyer 8