Class Notes- Exam 4 - Professor Jason Wiles PDF

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4/10/19 Ch.46: Animal Reproduction -

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Animal reproduction - Animal reproduction takes many forms - Ex: reproduce without any form of sex - Some organisms can change sex - In certain corals, individuals have both male and female organs - A population to live in members only by production, the generation of new individuals from existing ones. Both asexual and sexual reproduction occur in the animal kingdom - Sexual reproduction is the creation of an offspring by fusion of haploid gametes, male sperm and female eggs, to form a diploid zygote. - Asexual reproduction is the creation of offspring without fusion of egg and sperm Mechanisms of asexual reproduction - Budding is a simple form of asexual reproduction found only among invertebrates - New individuals arise from outgrowths of existing ones - Many invertebrates reproduce asexually by fission, separation of a parent into two or more individuals of about the same size. - Fragmentation is breaking of the body into pieces, some or all of which develop into adults - Must be accompanied by regeneration, regrowth of body parts - Parthenogenesis is the development of a new individual from an unfertilized egg - Mainly observed in invertebrates, but is observed rarely in some vertebrates Variation in patterns of sexual reproduction - For many sexually reproducing animals, finding a partner for reproduction can be challenging - In hermaphroditism, each individual has both male and female reproductive systems - Any 2 individuals can mate under this system, and in some species, hermaphrodites can also self-fertilize. - Several organisms can change their sex under certain circumstances Reproductive cycles - Most animals exhibit reproductive cycles related to changing seasons. - Controlled by hormones and environmental cues - Ovulation is the release of mature eggs at the midpoint of a female cycle. - Because seasonal temperature is often an important cue in reproduction, climate change can decrease reproductive success. - Some organisms can reproduce sexually, or asexually, depending on conditions - Several genera of fishes, amphibians, and lizards reproduce by a form of parthenogenesis that involves the doubling of chromosomes after meiosis

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Asexual whiptail lizards are descended from a sexual species, and females still exhibit mating behaviors.

Two-fold cost of sex - If each individual were to contribute to the same number of offspring (2), the sexual population remains the same size each generation, where the asexual population doubles in size each generation. - Despite this, almost all eukaryotic species reproduce sexually. Muller’s ratchet - A process by which the genomes of an asexual population accumulate deleterious mutations in an irreversible manner. Sexual reproduction: an evolutionary enigma - Sexual reproduction may enhance reproductive success of parents when environmental factors change relatively rapidly. - This is due to their reproduction of genetically varied offspring - Asexual reproduction is expected to be most advantageous in stable, favorable environments. Fertilization depends on mechanisms that bring together sperm and eggs of the same species - Fertilization, the union of egg and sperm, can be external or internal - External: eggs shed by the female are fertilized by sperm in the external environment - A moist habitat is always required for external fertilization to allow sperm to swim to the egg and to prevent the gametes from drying out. - Some species with external fertilization exhibit spawning, in which individuals cluster in the same area to release their gametes into the water at the same time - In some cases, chemical signals trigger spawning; in others, environmental cues are responsible - Internal fertilization is an adaptation that enables sperm to reach an egg despite a dry external environment - Requires behavioural interactions and compatible copulatory organs - Mating animals may make use of pheromones, chemicals, released by one organism that influence the physiology and behavior of individuals of the same species. Ensuring the survival of offspring - Internal fertilization is typically associated with production of fewer gametes but the survival of a higher fraction of zygotes - Also often associated with mechanisms to provide protection of …. - Internally fertilized eggs of birds and other reptiles have shells and internal membranes - These protect against water loss and physical damage as the embryos develop - Some animals retain the embryo, which develops inside the female

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- In many animals, parental care helps ensure survival of the offspring Gamete production and delivery - To reproduce sexually, animals must produce gametes from precursor cells - In most species, individuals have gonads, organs that produce gametes. - Some organisms do not have gonads, but gametes form from different undifferentiated tissue. - More elaborate systems include sets of accessory tubes and glands that carry, nourish, and protect gametes and developing embryos. - Most insects have separate sexes with complex reproductive systems - In many insects, the female has a spermatheca in which sperm is stored in copulation. - A cloaca is a common opening between the external environment and the digestive, excretory, and reproductive systems - Common in non-mammalian invertebrates; mammals usually have a separate opening to the digestive tract.

4/15/19 - Asexual reproduction - Single parent - Genes of offspring identical to parents (except for mutations) - Benefits - Energy efficient - Most successful i stable environment - Types of asexual reproduction - Budding - Part of the parent’s body grows, detaches - Hydra - Fragmentation - Parent’s body breaks into pieces - Each piece can develop into new animal - Planarian - Parthenogenesis - Unfertilized egg develops into adult - Tardigrades / water bears - Sexual reproduction - Fusion of two types of gametes (egg and sperm) produces offspring - A fertilized egg (zygote) - Benefits - Genetic variety - Adaptive in unstable, changing environment - Fertilization - External fertilization - Mating partners release eggs and sperm into water simultaneously

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Internal fertilization - Male delivers sperm into female’s body Male reproductive system - Testes (produce sperm and testosterone) - In the scrotum - Contain seminiferous tubules - Where sprmatogenesis (sperm production) occurs - Interstitial cells - Secrete testosterone - Sertoli cells - Produce signaling molecules and fluid that nourishes sperm cells - Conducting ducts - Epididymis and vas deferens - Sperm maturation and storage - Ejaculation of sperm - From vas deferens - To ejaculatroy duct - Into urethra through penis - Accessory glands - Semen - About 200 million sperm per ejaculation - Secretions of seminal vesicles and prostate gland - Bulbourethral glands - Release mucous secretion - The penis - 3 columns of erectile tissue - 2 cavernous bodies - 1 spongy body (surrounds urethra) - Erectile tissue engorges with blood - Penis becomes erect - Sperm structure - Head of the sperm consists of nucleus and a cap (acrosome) containing enzymes that help the sperm penetrate the egg - Production to ejaculation - Sperm pass in sequence through - Seminiferous tubules of the testis - Epididymis - Vas deferens - Ejaculatory duct - Urethra Female reproductive system - Ovaries produce - Gametes

- Steroid hormones- estrogen and progesterone Fertilization takes place in oviducts (uterine tubules) Uterus - Incubator for developing embryo - Endometrium - Epithelial lining of the uterus - Thickens each month for possible pregnancy - Cervix - Lower part of uterus - Extends into the vagina - Vagina - Can receive penis during sexual intercouse (for non-medically assisted reproduction) - Lower part of birth canal - Vulva - Labia majora - Labia minora - Vestibule of the vagina - Clitoris - Mons pubis - Breasts - Function in lactation (milk production) - Consists of 15-20 lobes of glandular tissue - Gland cells arranged in alveoli - Hormones - Prolactin stimulates milk production - Oxytocin stimulates ejection of milk from alveoli into ducts Oogenesis - In the ovaries - Oogonia - Differentiate into primary oocytes - Follicle - Consists of: - Primary oocyte - Granulosa cells surrounding it - As follicle grows - Connective tissue surrounding granulosa cells form layer of theca cells - As follicle matures - Primary oocyte undergoes first meiotic division, giving rise to secondary oocyte and a polar body Ovulation - Secondary oocyte ejected from ovary -

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- Enters an oviduct, where it may be fertilized Corpus luteum - A temporary endocrine gland - Develops from part of follicle remaining in ovary The menstrual cycle - Typically 28 days - Day 1 - Beginning of menstrual bleeding - Day 14 - Ovulation Estrogen - Responsible for primary and secondary female sex characteristics - Stimulates development of endometrium Without fertilization - Corpus luteum degenerates - Concentrations of estrogen and progesterone in the blood fall - Menstruation occurs -

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4/17/19 - Discrete sensory inputs can stimulate both simple and complex behaviors - 4 questions about animal behavior to be asked: - What stimulus elicits the behavior? - What physiological mechanisms mediate the response? - How does the animal’s experience during growth and development influence the response? - How does the behavior aid survival and reproduction? - What is the behavior’s evolutionary history? - Behavioral ecology is study of the ecological and evolutionary basis for behavior - Integrates proximate and ultimate explanations for animal behavior - Proximate causation addresses HOW a behavior occurs or is modified (Questions 1+2) - Ultimate causation addresses WHY a behavior occurs in the context of natural selection (Questions 3+5) - Fixed action patterns - A fixed action pattern is a sequence of unlearned acts directly linked to a simple stimulus. - Fixed action patterns are unchangeable and, once initiated, usually carried to completion - Triggered by an external cue known as a sign stimulus - Animal signals and communication - In behavioral ecology, a signal is a stimulus transmitted from one organism to another - Communication is the transmission and reception of signals between animals

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Animals communicate using visual, chemical, tactile, and auditory signals Fruit fly courtship follows a 3-step stimulus-response chain: - A male identifies a female of the same species and orients towards her - Visual communication: he sees the female and oreints his body towards her - Chemical communication: he smells the female’s chemicals in the air to confirm her identity - The male alerts the female to his presence - Tactile communication: he touches the female with a foreleg - The male produces a courtship song to inform the female of his species - Auditory communication: he extends and vibrates his wing - If all 3 steps are successful, the female will allow the male to copulate. Learning establishes specific links between experience and behavior - Innate behavior is developmentally fixed and does not vary among individuals Learning - = the modification of behavior based on specific experiences - Contributions of nature and nurture in shaping learning and behavior ? → research Associative learning - Animals associate one feature of their environment with another - Ex: blue jay will avoid eating monarchs and similar looking butterflies after an experience with a distasteful monarch butterfly. - Classical conditioning is a type of associative learning in which an arbitrary stimulus is associated with a reward or punishment - Ex: Pavlov, dog + bell - Operant conditioning is a type of associative learning in which an animal learns to associate one of its behaviors with a reward or punishment - AKA trial and error learning - Ex: rat fed after pushing lever, learn to push lever to get food - There is some restriction to the type of associations that can be formed between environmental stimulus and behavior. - Ex: rats can learn to avoid illness-inducing foods on the basis of smells, but not on the basis of sights or sounds. Development of learned behaviors - Development of some behaviors occur in distinct stages over time - Ex: white-crowned sparrow memorizes the song of its species during an early sensitive period - Bird then learns to sing the song during a second learning phase Social learning - = learning through the observation of others - Ex: young chimpanzees learn to crack palm nuts with stones by copying experienced chimpanzees

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Ex: young vervet monkeys learn from older monkeys to give and respond to distinct alarm calls for different predators - Culture is a system of information transfer through observation or teaching that influences behavior of individuals in a population - Can alter behavior and influence the fitness of individuals Selection for individual survival and reproductive success can explain diverse behaviors - Behavior enhances survival and reproductive success in a population - Natural selection refines behaviors that enhance the efficiency of feeding - Foraging, or food-obtaining behavior, includes recognizing, searching for, capturing, and eating food items. - Optimal foraging model - Views foraging behavior as a compromise between benefits of nutrition and costs of obtaining food. - Costs: expending energy, risk of being eaten while foraging - Natural selection should favor foraging behavior that minimizes the costs and maximizes the benefits - Ex: elk mating display - Chimpanzee group behavior Mating behavior and mate choice - Play a major role in determining reproductive success - Includes seeking or attracting mates, choosing among potential mates, competing for mates, and caring for offspring Mating systems and sexual dimorphism - Mating relationships define a number of of distinct mating systems - Promiscuous: no strong pair bonds - Monogamous: one male mates with one female - Tend to have similar external morphologies - Polygamous: an individual of one sex mates with several individuals of the other sex - Usually sexually dimorphic: males and females have different external morphologies - Either polygynous or polyandrous - Polygynous : one male mates with many females - Males are usually more showy and larger than the females - Polyandrous : one female mates with many males - Females are often more showy than the males Mating systems and parental care - The needs of the young are an important factor constraining evolution of mating systems - Consider bird species whose chicks need a continuous supply of food - A male maximizes his reproductive success by staying with his mate and caring for his chicks (monogamy)

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Consider bird species whose chicks are soon able to feed and care for themselves - A male maximizes his reproductive success by seeking additional mates (polygyny) - Certainty of paternity also influences parental care and mating behavior - Females can be certain that eggs laid or young born contain her genes - Paternal certainty is low in species with internal fertilization because mating and birth are separated over time - Ex: male frogs when mounting female frogs are certain that their gametes fertilized with the females’ - Much higher when egg laying and mating occur together, as in external fertilization - Species w external fertilization : parental care is at least as likely as to be by males as by females Sexual selection and mate choice - Sexual dimorphism results from sexual selection - Sexual selection is a form of natural selection in which differences in reproductive success result from differences in mating success - INTERsexual selection: members of one sex choose mates on the basis of certain traits - INTRAsexual selection: involves competition between members of the same sex for mates - Mate choice by females - Type of intersexual selection - Can drive sexual selection by choosing males with specific behaviors or features of anatomy - Ex: female stalk-eyed flies choose males with relatively long eyestalks - Ornaments, such as long eyestalks, often correlate with health and vitality. - Mate choice can also be influenced by imprinting - Ex: female zebra finch chicks show no preference for male ornamentation when raised by fathers without ornamentation. - Female chicks raised by fathers with artificial ornamentation (red feather) preferred ornamented males as mates - Mate choice copying is a behavior in which individuals copy the mate choice of others - Ex: experiments w guppies- choice of female models influenced the choice of other females - This behavior may serve to increase the attractiveness of the offspring to the opposite sex. - Mate competition for mates: - Source of intrasexual selection that can reduce variation among males

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May involve agonistic behavior, an often ritualized contest that determines which competitor gains access to a resource. Genetic variation and evolution of behavior - When behavioral variation within a species corresponds to environmental variation, it may be evidence of past evolution

4/22/19 -

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Early human development - Fertilization - Occurs in the oviduct - Cleavage - Takes place as embryo is moved down the oviduct - Blastocyst - Develops in the uterus Blastocyst - Outer trophoblast - Gives rise to chorion and amnion - Inner cell mass - Becomes the embryo proper - Blastocyst undergoes implantation - In the endometrium The placenta - Organ of exchange - Between maternal and fetal circulation - Derives from embryonic chorion and maternal tissue - Umbilical cord - Connects embryo to placenta - Maternal and fetal blood NEVER MIX - Materials diffuse across the membranes *when a secondary oocyte is fertilized, development begins nd the embryo implants in the wall of the uterus; hormones from the developing embryo, from the corpus luteum, and laer from the placenta maintain the pregnancy* Early development - First 2-3 months of pregnancy - Corpus luteum secretes large amounts of estrogen and progesterone needed to maintain pregnancy (maintains endometrium (lining of uterus)) - … Parturition - The birth process - Regulated by hormones (positive feedback loop) - Estrogen - Oxytocin

- Prostaglandins Labor - Divided into 3 stages - Baby is delivered in the 2nd stage Contraception - Effective methods - Hormone contraceptives (oral, injectable progestin) - Intrauterine devices (IUDs) - Condoms - Contraceptive diaphragms - Sterilization (vasectomy, tubal sterilization) Sexually transmitted diseases (STDs) - Human papillomavirus (HPV) - Chlamydia (pelvic inflammatory disease) - Genital herpes - Gonorrhea - Syphilis - HIV -

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Animal behavior - Behavior - What an animal does and how it does it - Usually in response to stimuli environment - Proximate causes (immediate causes) - Genetic, developmental, physiological - Permit animal to carry out specific behavior - Answer how  questions - Ultimate causes - Answers why  a certain behavior occurs - Cost benefit analysis - Used to determine if a behavior is adaptive - Benefits contribute to direct fitness - Animal’s reproductive success - Measured by number of viable offspring - If benefits outweigh costs, behavior is adaptive - Natural selection is essentially a cost-benefit analysis - Heredity and environment - Behavior Results from - Interaction of genes (innate behavior) - Environmental factors - Capacity for behavior is inherited - But modified in response to environmental experience - Maturation

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For an organism to perform a pattern off behavior it ...