Animal Reproduction PDF

Animal Reproduction Vertical Gene Transfer Reproduction aseX -7. Jex. neum...

Animal Reproduction Vertical Gene Transfer Reproduction aseX -7. Jex. neum hodistin distinct sexs -- 1 externa internal fertilization fertilization Introduction Hydra with buds Reproduction involves the production of offspring, passing genetic information down Asexual reproduction does not require gametes (sex cells) and is in essence cloning (budding, fission, fragmentation, parthenogenesis) Sexual reproduction requires gametes (produced via meiosis); typically small, motile sperm and larger, non-motile eggs Sexual Reproduction can do both - sex's a sex reproduction Hermaphroditism allows an ① individual to produce both eggs change sex and sperm produce gametes both multiple ② More commonly distinct sexes change Jex once (dioecy) each produce one type of gamete (females producing ③ eggs and males producing sperm)  strongly governed hormones by - Sexual Reproduction Con’t Reproductive events (maturation, ovulation) are often closely controlled by hormones to properly time the production of offspring (both sexually and asexually) spring ex. is best time Offspring typically produced when food/resources are abundant to have babies Despite being less efficient at passing on genes, and more risky, sexual reproduction is quite common in animals, likely due to the advantage of variation in offspring it produces Expect more sexual reproduction in highly varied environments/conditions ( Expect more asexual reproduction in stable environments/conditions chance of it since variation produced - > evolution keep  Gamete Production Most gametes are produced in gonads (gamete producing organs) Structures used to distribute gametes can be quite complex: specialized Spermathecae in female reproductive tracts store sperm in some insects, allowing her to mate once and pouchoerm then portion out sperm over time for Queen bees will mate early in life to collect sperm (typically from multiple males) and then produce fertilized eggs until death from that supply Fruit flies (and at least some spiders) only fertilize eggs with stored sperm when conditions are good [and sometimes they choose a second mate – the first one may be an insurance policy!]  Fertilization Fertilization (fusion of sperm with egg) can be external (in the environment) or internal (within the reproductive tract) External is simple, useful in water-based ex , frogs , barnacles , environments (sperm swim to find eggs) - urching leak out Timing is often very important & gamete production gamete tends to be very high (with high mortality); may benefit sessile or not very motile animals Example: spawning events Internal is useful in dry environments but requires more complex anatomy Courtship may be more important & gamete production must court to - sexually engage tends to be lower (with lower mortality) May also involve internal embryonic development Human Reproductive Systems - essential for passing genes i Male anatomy Testes (scrotum) - gonads Epididymis Vas deferens Ejaculatory duct Urethra Glands: compose ejactulate Seminal vesicles Fructose/alkaline fluid/ prostaglandin fuel moving Prostate only 1 (no duo part) sperm Enzymes to prevent thickening anti Bulbourethral could its Lubricant/neutralize urethral acidity = precum Penis make clear pathway to sperm · composed of spongy tissue · more blood = erect Human Reproductive Systems Female anatomy Ovaries Follicles Corpus luteum directly connected Oviduct/fallopian tube not Uterus (embryo -> fetus) Endometrium nurture + issue designed to baby Cervix barrier to keep baby safe External genitalia Vagina (9 Labia minora/majora (ruiva) Clitoris xurinary sys separate. in females uretura baby pushes on bladder Making Gametes ~ production of sperm Spermatogenesis occurs in seminiferous tubules of the testes Via mitosis, cells differentiate into primary spermatocytes Via mieosis I, primary divide into 2 chromo. halfed secondary spermatocytes identical copry ! Via mieosis II, each secondary diploid > - haploid spermatocyte develops into a sperm constana cell Cells Start at outer ring, end at center  Making Gametes set number of > eggs Oogenesis occurs in the ovary - Each follicle has one primary oocyte > - stopped at mitosis (diploid) prepared for meiosis I 20 FSH stimulates development O O (meiosis I) to unevenly distribute cytoplasm into 1st polar body useless polcir (small) & secondary oocyte (big) - stops at metaphase II Secondary oocyte is ovulated into oviduct; if sperm fuses, completes meiosis II to release 2nd polar body & haploid ovum (becomes fertilized) Sex Hormones Gonadal Male: Hypothalamus signals to anterior pituitary (gland) > - dumps hormones ( Release follicle stimulating same system hormone (FSH) & luteinizing in males females hormone (LH) to testes FSH stimulates sperm production in - Sertoli cells LH leads to release of androgens (ie testosterone) from Leydig cells Both inhibin and testosterone act - in negative feedback loops, allowing continuous but stable sperm production S negative feedback inhibits innibin Sex Hormones Female: Ovarian cycle stimulates egg development Uterine cycle regulates endometrial development (menstrual cycle) Still using FSH & LH, the hypothalamus, & anterior pituitary gland (like in males) BUT with ovaries and estrogen + · progesterone Note that estrogen acts in negative feedback loops normally, but briefly in a positive manner, resulting in cyclical egg release (ovulation)  Putting it Together Menstruation: shedding of uterine endometrial lining (if no viable pregnancy) Endometrial tissue growing outside the uterus = -endometriosis hormones surge behaviors Humans do not have - change or sometimes estrous (heat) cycles, but appearance behavior may be influenced - by cycles (PMS, PMDD) of Menopause: end of significance x proestrone menstruation whole system shut down no menstration for a year demure  - big pad that splits into 5 fingers Embryonic Development  Fertilization Fusing of male and chromo female gametes > - 23 (haploid sperm + egg) to form diploid zygote 2 sets ↳ of undergoes 23 chromosome cell division Sperm anatomy Head (acrosome & nucleus) main DNA - Neck/midpiece - connects head to flagellum (mitochondria) to energy > - autility Flagellum ↳ long whip-like ; helps sperm swim L multiple sperm trying to get to egg Preventing Fertilization fertilization chances -reduce Contraceptives (reduce chance of pregnancy) Oral (birth control pill) hormonal ; daily - Intrauterine device (IUD) Implant Diaphragm Condoms NOT contraceptives: Plan B (“morning after pill”) makes implantation less likely (