{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

classnotes10 - Reproduction Methods of reproduction asexual...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Reproduction: Methods of reproduction: - asexual. This only involves a single animal, and the genes of the offspring all come from the parent (without going through sperm/egg fusion). - sexual. Involves fusion of egg and sperm to develop a zygote. A zygote is the cell that results from fusion of egg and sperm. Asexual: - fission - the parent splits into two more or less equal halves. Each half then goes on to grow and mature. - budding - generally similar, but here the parent may bud off new individuals that are smaller than parent. This new individual may remain attached, or separate. - corals (cnidarians) - young stay attached. - hydra (also cnidarians) - young detach. - fragmentation - the body breaks into several pieces, each of which can form a new individual. [This does not include merely re-growing limbs (or tail)]. Starfish example. Some animals may reproduce both sexually and asexually. Corals again are a good example. In general, sexual reproduction is used during more stressful times, and asexual reproduction when times are good (why?). Parthenogenesis: - Egg develops without being fertilized. Resulting individual may be haploid or diploid, depending on whether or not haploid egg doubles before developing. - occurs in many animals, e.g. Rotifers, Daphnia, and whiptail lizards. Sexual reproduction - obviously, fertilization is required. Sperm must meet up with and fertilize egg. - problem for sessile organisms. How to transport sperm?? E.g., tapeworm. - one solution -> hermaphroditism. A hermaphrodite has both female and male reproductive structures. This makes it easier to find a mate. Also, since two individuals can exchange sperm, potentially twice as many offspring can be produced (though this is really a bit more complicated than that!!).
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
- sequential hermaphroditism. Some fish can change sex during lifetime. This depends on whether large size may be an advantage - e.g. in some fish males defend territory, so they need to be larger. Just be aware that this exists. - methods of fertilization: - external - union of sperm and egg occurs outside the body. Typically, eggs are released by the female, then the male covers the eggs with sperm. Many animals will do this (frogs, many fish, etc.) - internal - sperm are deposited in or near the female reproductive tract, and fertilization occurs within the female reproductive tract. - note: many mechanisms are in place to insure that mating takes place only within the same species - behavior, pheromones, environmental cues - for vertebrates (and some others), we can consider the following breakdown as well: - oviparous - animal lays egg, embryo develops within egg, egg hatches.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern