Chapter 46 notes

Environmentalcues changesindaylength changes in

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Unformatted text preview: $$$$$$$$$$$$$$$$$$$$Reproduc8ve$cycles$ Common!Environmental!Cues:! Changes$in$day$length$ *$Changes in seasonal temperature Changes$in$rainfall$ Changes$in$lunar$cycle$ These cues are processed in the brain and trigger the release of HORMONES that begin the reproductive cycle! Animal(reproduc5on(takes(many(forms( Both(sexual(and(asexual(reproduc5on( Example:((Daphnia$–$females$can$produce$two$types$of$eggs$ 1.  Egg$require$fer8liza8on$to$develop$(environment$is$stressed)$ Egg 2.  $$ develops by parthenogensis (environment is STABLE) Hermaphrodi5sm$–$both$male$and$female$reproduc8ve$systems$ Example:$$Earthworm( Has sperm AND egg. Common$in$sessile$organisms$ Sessile: largely non-motile Why?( They can't find a mate easily since they're stationary… so its beneficial to have both gametes so it can fertilize on its own and reproduce. Sex(Reversal( Whoa….. Example:((blue(headed(wrasse,(Thalassoma(bifasciatum( Live$in$harems$consis8ng$of$1$male$and$several$females$ When$male$dies,$largest$female$becomes$a$male$(produces$ sperm$instead$of$eggs)$ Fer5liza5on:$$union$of$sperm$and$egg$ $ External(Fer5liza5on:((Eggs$are$released$into$the$environment,$where$the$male$fer8lizes$them$ *$ Requires MOIST habitat Requires$8ming$to$ensure$mature$egg$and$sperm$encounter$one$another$ - Lots of behavioral patterns need to match up Synchronous(across(a(popula5on:((Spawning$$ $releases$eggs$and$sperm$at$same$8me/loca8on$ $ Nonsynchronous$ Requires individual mating behavior! Doesn't happen @ same time/place Internal(Fer5liza5on:((an$adap8on$that$enables$sperm$to$reach$eggs$efficiently,$even$when$the$ environment$is$dry$ Requires$coopera8ve$behavior$that$leads$to$copula8on$ *$ Requires compatible reproductive systems -- must be able to mate lol Reproduc5ve(Organs:((Pr...
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