Reproduction Flashcards
All Metazoans reproduce asexually? T or F?
False, they reproduce sexually
Sexual reproduction
Requires meiosis and gamete fusion; daughter cells form unique gametes; meiosis produces haploid while gamete fusion produces diploid
Ansiogamy
Different sized gametes; common in animals and plants
Isogamy
Same sized gametes; common in protists
Asexual reproduction
Doesn’t need sex; involves mitosis creating identical daughter cells; ancestral for all eukaryotes; no need for another individual’s gametes
What are the three ways for asexual reproduction?
Budding, fragmentation, and fission
Budding
Growing a new organism directly from original organism; deliberate and plant-like; produces exact same; Ex: hydra
Fragmentation
When cut off it produces another organism; accidental; Ex: sea star
Fission
Similar to budding; splits in half; planned Ex: coral polyps
Why did sexual reproduction evolve?
Genetic recombination allowed for increased genetic diversity as well as compensation for bad mutations.
Asexual vs Sexual Reproduction
Asexual: faster, no partner needed, mitosis based, highly effective in stable environments, passes on whole genome
Sexual: slower, needs a partner (unless it is a hermaphroditic), meiosis based, high genetic diversity aids local adaption, passes on half of genome
Hermaphrodites
Have male and female gametes; has two types: simultaneous hermaphrodites and sequential hermaphrodites
Simultaneous hermaphrodites
Have testes and ovaries at the same time; always producing games of both genders; might self-fertilize for preservation; Ex: killifish and banana slug
Sequential hermaphrodites
Starts as one sex then transitions due to social cues; Ex: clownfish and Catalina goby
External fertilization
Needs water; releases gametes in environment for them to meet each other; also called spawning; Ex: fish and amphibians
Internal fertilization
Gametes meet inside an animal; Ex: salamanders, insects and birds
Salamander example for internal fertilization.
Male salamander leaves a spermatophore (sperm) for female to pick up and take in for fertilization
Sexual conflict
Some females do not want to fertilize w/ males; sometimes vaginas do not fit w/ penis making it unable to reproduce; Ex: swans, geese and ducks
Spermatheca
Only in animals that do internal fertilization; females store sperm in these structures; Ex: chicken and fruit fly
What are benefits of sperm storage?
Control time of fertilization/delaying it, sperm selection, if male is infertile
What is the order of development in stages?
Fertilization (fertilization -> cleavage), Morphogenesis (Blastulation -> Gastrulation -> Organogensis), Growth
Blastulation
Forming germ layers (diplomas tic and triploblastic)
Gastrulation
Forming digestive tract (protostome or deuterostome)
Organogenesis
Cells differentiate into organs
Examples of parental care.
Guarding eggs, providing shelter/food, long term bonds help enhance offspring survival
