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FYS Final Study Questions
Terms in this set (41)
Why is the concept of a 'sperm race' misleading?
Sperm do not race to the place of conception. Orgasmic and other contractions alter the fluid dynamics of the female reproductive
tract and propel or impede sperm as appropriate. Female secretions nurture suitable sperm and biochemically alter sperm to enable conception. Portions of the tract are used for sperm storage.
In general, once a female obtains sperm, she manages their activity and function. For the most part, sperm are passive recipients
Comment on the why the term 'induced ovulation' is misleading.
The term induced ovulation is misleading, because it is male centric. Induced ovulation is when ovulation occurs after copulation. It makes it sound like males cause ovulation, when females have control over the process. In fact, Luteinizing hormones which triggers ovulation can also trigger mating, which shows how females are in control (ovulation induces mating).
What is a primordial germ cell?
Primordial germ cells are cells in the embryo destined to become the next generation of gametes when the embryo becomes an adult.
Describe how oogenesis and folliculogenesis differ.
Folliculogenesis: changes in ovarian tissue. Follicles are aggregations of maternal cells. Mitosis.
Oogenesis: formation of female gametes. Oogenesis creates cells that contain half the maternal nuclear genome, as well as all of the maternal mitochondrial genome, a plethora of cytoplasmic organelles, and accessory materials of maternal origin (meiosis). Each oocyte is a single cell.
How do secondary oocytes and secondary follicles differ?
-Secondary oocytes have half of the genetic material. -Secondary oocytes are only one cell (grow in size)
-Secondary follicles are maternal cells (have full genetic material.
-Secondary follicles are multiple cells, so they are growing in the number of cells and the complexity of the constituent layers, including the granulosa, basal lamina, and thecal layers. Some follicular development is by mitosis (cell multiplication) of established follicular cells, but other development is by recruitment and subsequent differentiation of neighboring ovarian cells
Explain how 3 generations may exist in the same place and time.
3 generations may exist in the same place, because the mother can be pregnant with her daughter which has the primordial germ cells (potential grandchildren) all in one space.
What are confusing features of diagrams of oogenesis vs folliculogenesis?
Oogenenis diagram--> says polar body "dies," but that's not possible. It degenerates.
There is similar naming that is confusing. "Primary oocyte" and "primary follicle" (etc.) makes it seem like you find a primary oocyte in the primary follicle, but that is not true. It is hard to tell what is mother vs potential offspring.
Why are ipsilateral and contralateral inhibition important to ovulation?
Ipsilateral (within the same ovary) and contralateral (in the other ovary) inhibition are important to ovulation, because it makes sure that only one ovum is ovulated each time (important for singleton births).
What are the two phases of gestation in therians? How do they differ from one another with respect to fetal vs maternal control?
Two phases of gestation in therians are conception to implantation and implantation to birth. Maternal control for conception to implantation phase. Fetal control for implantation to birth phase.
How does implantation change the dynamic of gestation?
Implantation marks a transition from the relative autonomy of offspring and mother to an intricate fetal and maternal interdependence. Before implantation, the maternal physiology alone, more or less, determines if pregnancy will continue, after implantation, the conceptus and its siblings can influence that process via placental attachment.
What are the phases of embryogenesis in monotremes? How do they differ from those in therians?
The two phases of embryogenesis in monotremes are conception to egg laying and egg laying to egg hatching. Egg laying is not at all equivalent to implantation. For monotremes, more development is done between conception to egg laying compared to in eutherians where most of development happens from implantation to birth. It is also less clear if egg laying or egg hatching is comparable to birth. It depends on which perspective (mother or offspring).
What are two type of delays that can occur during gestation? Name 3 species with gestational delays. What are 2 possible advantages of delays during gestation?
2 types of delays:
-Delayed conception (sperm storage)
-Delayed implantation (blastocyst implantation delay)
3 species with gestational delays:
-Female little brown bats can store sperm for up to 128 days
-Female eastern quoll can store sperm for 14-16 days
-Tammar wallabies (delayed implantation for up to 11 months)
-Can chose best conceptus (delayed conception)
-If there are harsh environments/to be able to feed older progeny (delayed implantation)
Are gestational delays common among mammals? Why or why not?
Yes, gestational delays are common among mammals. All females store sperm for anywhere from a few hours to several months. Also, delayed implantation affects 30-40 marsupials and 95 eutherians during the pre embryo stage.
What are 2 advantages of a shelled egg? What are 2 disadvantages?
2 advantages of a shelled egg--> Gives protection and nutrient transfer
2 disadvantages of a shelled egg--> Eventually, egg shell can't provide enough nutrients to offspring and has to deal with the outside while embryo is still developing
What are the 4 major ways in which mammalian mothers provision their young?
The 4 major ways in which mammalian mothers provision their young are through yolk, uterine secretions, placentation, and lactation.
What happens between conception and implantation?
Pre-implantation is a period of embryonic cell division, much of which occurs while the zygote is still enclosed within a maternally derived, protective membrane, the zona pellucida. The conceptus can receive uterine secretions to develop more. The conceptus moves around a lot before attaching, which is necessary for continuing the pregnancy. Finally, the embryo implants.
Why is uterine spacing important to mothers? To offspring?
Uterine spacing is important to mothers, because there is less sibling competition, it is easier for mobility. This is good if the mother has to evade predators or has to jump a lot.
Uterine spacing is important to offspring, because there is less sibling competition. It also keeps litter size down.
What is a freemartin? What does it tell us about gestation?
Freemartin: females that develops behaviors and growth patterns associated with steers, because twins of different sex in utero (happens in farmed ungulates). This tells us how important implantation can be, because Uterine position and the sex of adjacent siblings may influence neonatal size, degree of sex dimorphism, postnatal growth, and behavior, as well as adult physiology
For monotremes, is egg-laying or hatching comparable to birth? Explain your reasoning.
Egg laying more comparable to birth:
-The Physical Process--> For Eutherians, the mother's
cervix has to dilate and she must
have contractions for birth to occur, For hatching the mother, has to expel the egg
-Maternal Control is Paramount--> Neonate is in the egg so it cannot influence birth, Several factors can lead to the Eutherian mother having more control
(small mammals/mammals with multiple neonates in a litter)
Hatching more comparable to birth:
-Physical Process--> In Eutherians, the neonate must
orient it self, In monotremes, the neonate has to use an egg tooth to break out
-Suckling--> Eutherians suckle after birth, At least for echidnas, neonates suckle after hatching
-Fetal Control is Paramount--> Monotreme mothers do not directly hatch the egg, Several factors can lead to the Eutherian neonate having more control (Larger mammal/Single litter)
Who controls birth mother or offspring? Explain your reasoning?
Monotremes--> Depends on what is considered birth: egg laying or egg hatching (Egg laying = Maternal control and Hatching = Offspring control)
Marsupials--> There is contrasting evidence for both maternal and offspring control of birth - Maternal control (In tammar wallabies, removal of maternal pituitary gland prevents birth), Offspring control (In tammar wallabies, prostaglandins from the placenta trigger birth)--> A recent review of progesterone in marsupials suggests that offspring initiate birth
Eutherians--> Different factors of who controls birth--> Neonates are precocial (fetal) or altricial (maternal), Singleton (fetal) vs litter (maternal), Small species (maternal) vs large species (fetal)
How do births of litters differ from those of singletons?
Singleton births--> Often happens in exposed circumstances, lack of sibling competition (Can grow large in the uterus/Less worry about finding a teat), Still influenced by older siblings (Facultative delays due to nursing older siblings), Birth length has a designated length from contractions to release of the offspring
Litter births--> Litter birth mammals birth in unexposed circumstances. They hide in crevices, tree cavities or nests to conceal themselves from predators, The process of birth in a litter is maternally controlled (reduce sibling competition, mother size (small)--> small species, maternally controlled), Litters have a series of births with periods of recovery between each birth. Is birth considered each single birth or from the first to the last?
What is placentophagia? What are advantages of placentophagia?
Placentophagia: Consumption of the placenta and/or afterbirth by mother and in some cases, father.
-The placenta is an organ developed during the stages of pregnancy that has the role of supporting the baby with oxygen and nutrients, while carrying out waste products. It attaches to the wall of the mother's uterus. The placenta is also responsible for creating hormones crucial for managing pregnancy and protecting from infection
Advantages of placentophagia: Energy, water, nutrients, Hormonal role in recovery (Ex.: prostaglandins, oxytocin), Hormones can also help with bonding to offspring, Opioids can make subsequent births of siblings easier, Removes odors that could attract predators
What is the function of a neonate's pelage?
Pelage can be defined as the wool, fur, or hair of a mammal
-While the function of pelage varies for adults, one of the main purposes for new infants is for the fur to serve as camouflage for protection
-Pelage can also serve as a social signal to promote infant care
-Obscure clues to paternity which decreases the likelihood of infanticide
-Pelage can also change over time
In what ways is the marsupial neonate more advanced than the eutherian neonate?
Marsupial birth--> Marsupials have a short gestation length meaning the offspring is not well- developed at birth, After birth, marsupials crawl (using smell and sense of gravity) on their mothers to find her teats, so their front limbs must be well-developed, Marsupial neonates stay in the mother's pouch for long periods of time to further develop
Eutherian birth--> Eutherians are placental mammals, meaning that the fetus is fed by the placenta during gestation, Eutherian offspring are carried in-utero until well-developed
-There is some research that indicates that marsupial fetuses control the length of gestation and birth by increasing the amount of progesterone in the mother's blood stream.
-Marsupials have a more developed sense of smell
-They may control gestation length and birth
What organs and systems are involved in the physiology or process of birth?
Eutherian birth involves components of the maternal and fetal immune systems, hypothalamic-pituitary-adrenal axes, the neuromuscular systems, and the placenta. Birth is accompanied by an immune response, because the process of birth provides a major avenue for pathogens to enter the mother's body. The placenta has its own microbiome, and during birth all these microbial communities, maternal and placental, come into contact and provide the offspring with a starting microbiome.
-the cervix must dilate; placental structures must separate from the uterus; offspring must be oriented appropriately; if several pups are to be born, a birth order needs to be established; offspring need to be expelled/released one at a time; placental structures must be expelled/released; uterine contractions need to occur without crushing any offspring still in utero; the afterbirth and other debris must be removed; the newborns must be cleaned, and the first suckling
What are inherent problems with the terms precocial and altricial?
-Altricial refers to a neonate that is very dependent on its mother and less developed than a precocial neonate
-A precocial neonate is less dependent on its mother and is generally well developed when compared to an altricial neonate
Problems with altricial:
-The whole categorization is more of a spectrum than a dichotomy (Neonates can be more or less developed than other altricial neonates)
-A taxonomic bias is present when categorizing across species (Bats don't need sight but olfactory senses are more important)
-Anthropogenic bias in present as well (Humans are the ones categorizing neonates--> We prioritize things that are important to humans rather than mammals in general)
-When more than one neonate is birthed per litter, they are classified as altricial (Resources shared in the womb)
Problems with precocial:
-Relative, dependent on context
-Restricted to neonates which "exhibit advanced
sensory or locomotor abilities" (Marsupial neonates-- olfactory abilities, crawl to the teat at birth)
-Large number of developmental categories over a dichotomy
-Blubber over fur
-Unique lifestyles and requirements
Are offspring expelled or released during birth? Explain your reasoning.
It depends on who controls birth
What are the consequences of lactation?
Consequences of lactation includes a high energy expenditure, more food consumption, and foraging obstacles (Young that are being nursed in dens or nests restrict the mother from foraging-->Time/Place and Returning, feeding, & safety), Lactating females may experience lack of minerals and vitamins (ex: calcium) and oxidative damage, Mobility and relocation of the offspring becomes a big risk to predation.
How is 'first solid food' similar to 'implantation'? How does it differ?
-Both separates two different phases (Implantation separates gestation into two parts (in utero development) and Solid food also separates developmental growth into two parts (Different reliance on the mother--> From direct lactation to relying on the mother to bring solid food)
-Both implantation and the transition to solid food are periods of exponential growth (In utero, the implantation marks the start of gestation and In offspring development, the start of solid food consumption marks the start of independence from mother)
-Difference in mechanisms (Metabolic control in the transition to solid food and Physiological control in implantation)
-Difference in causes (Transition to solid food is a selective pressure and Implantation is an evolutionary
-Different reliance on the mother in the two transitions (In the solid food transition, the offspring relies less on the mother than when it did during lactation and In the gestation transition, the offspring becomes more directly reliant upon the mother once implantation has occurred)
Explain the burdens of lactation?
Risks created by lactation--> Having to carry pups or stay in the same area as a den limits mobility, Predation is more likely when females are vulnerable suckling young, Other members of the the female's social group can help protect and provide for her during lactation
Calcium deficiency--> Providing calcium to young may deplete the mother's store of it, Lack of calcium can weaken bones, Calcium deficiency is a big problem for animals that have diets of insects and fruits, such as anteaters and bats
Metabolic Burden--> Making milk requires energy (Find/catch food→ digest food→ transport to mammary glands→ add water→ store milk), Needs to collect more food (amount is species dependent) during gestation or during lactation
What are the functions of lactation? How does lactation accomplish those functions?
-Physical functions--> Used for offspring growth, daily physiology, storage, supporting activities, Different uses of components (calories-> activity,
minerals-> stored or growth)
-Different Tactics of Milk Usage--> Antarctic fur seal pups use milk for growth and neurological development and Subantarctic fur seal pups use
milk for adipose tissue (ASFP have to forage
independently at 4 months, SASFP have access to milk for 10 months, but only 3-4 days every 2- 4 weeks (have to fast))
-Composition of Milk--> Relative amounts of fats, carbohydrates, proteins, minerals, vitamins, and water vary greatly (Ancient differences-- diet), Milk changes to accommodate the current needs of the offspring (Marsupials-- more proteins in milk while young develop hair and claws)
-Non-nutritive Functions--> Maintained contact between mother and young allows for: Mother-offspring bonding, Socialization/Integration into social
roles, Protection from predation, Learning about food, migration routes, and safe havens
Milk changes in composition. What are some examples?
Ancestry--> The the genetic cross breeding of the Ankole and Holstein cattle showed that the European ancestry of the two breeds caused the decrease in milk yield within the cross breed. The cow's adaption to her environment over long periods of time result in the difference in milk composition and yield
Species--> Marsupials: Lactation is the major component of their reproductive biology, and milk is central in the growth and development of young, Primates: Lactation has a significant social function.
Milk is less important than the nursing and maternal proximity that accompany it, Tammar Wallaby: Three stages of 100 days--> First 100 Days--neonate primarily attached to the teat and receives dilute milk (low in fat and high in sugars), Next 100 Days--young releases from the teat but is in the pouch and suckles less frequently, Last 100 Days--young leaves the pouch and begins to eat grass and suckles less frequently, but very aggressively
Diet--> Herbivores: Rely on intestinal microbiome to digest materials (Cellulose) and Absorb the products of microbial digestion, Carnivores: Do all of what herbivores do (skip the microbial fermentation)
Different composition of carbohydrates, fats, proteins, minerals, vitamins
How does lactation control offspring?
Milk influences behavior--> Milk can affect the temperment of the offspring, There may be a connection between the mother's milk, the offspring's intestinal microbes, and the offspring's behavior
Nursing influence on behavior--> Different pheromones can be secreted in order to help neonates better locate the nipples. This phenomenon also promotes the offspring to learn environmental cues, allowing them to learn about their surroundings without leaving the safety of their homes
Sibling competition for mammary glands--> Finite number of mammary glands, benefit future offspring as the milk becomes easier to produce.
What do offspring do with milk once they get it?
Growth--> Increased size, Learning skills (neurological development)
Storage--> Fat for warmth, Preparation for fasting, Mineral storage
Activity--> Play, Foraging practice, Following mother, Forming social bonds
Different species have different uses of milk: Factors of function of milk--> weaning ages, access of milk (frequency of milk), body size (length of lactation), location (env), growth of offspring (some use lactation instead of gestation for development)
Provide a practical, definition of weaning that could be applied in a non-captive study of one of your species.
In general, weaning is the transition from mother's milk to eating solid foods (different definition for different perspectives)
Offspring: Leaving the natal den, first time consuming solid food, dispersal from native den/nest, ability to maintain weight after isolation from mom, independence (getting food/survival)
Mother: Cessation of lactation, Reduction in frequency or duration of suckling periods, Ability to conceive another litter, Time when mother leaves her litter
Bottlenose dolphin: nurses for 2-3 years until has new baby and weans the older one, start learning how to catch fish (snacking--> starts at few months old)
Moose: Weaned at 6 months, stays with mom for 1 yr (mom drives them off to give birth to next calf) (bulls wean sooner and end up further from mom than calves)
Wolves: Around four to six week old wolves are weaned off of mother's milk and start to eat meat. Adult wolves will bring food back to the den for the pups to eat. The adult wolf regurgitates the meat for the pup. All wolves in a pack will help to feed the pups. The pups stop drinking mother's milk by around eight weeks.
What is parent-offspring conflict? How is does this conflict differ for litters vs singleton young?
Parent-offspring conflict: when the best time to start weaning for each animal--> offspring wants to receive maternal care for as long as possible and mother wants to use the resources she's using for lactation for other purposes (New litter/own survival)
Singletons: The mother is more likely to get pregnant while lactating if the birth is a singleton, Pregnancy decreases the time the mother spends nursing the first born, The mother wants to provide resources for the new conceptus, The first born still wants as much maternal care as possible
Litters: Mother's must decide to provide resources to current offspring or save them for later litters, The birth of a second litter may influence the timing of weaning for the first litter (Suckling can cause delays in the birth of a later litter), Kin selection mediates some conflict
What happens between weaning and puberty? What determines the length of that interval?
What happens between weaning and puberty:
-For the mother the period of intense investment and daily input into the offspring stops, and so the energetic burden is shifted to the offspring. The offspring must now search for its own food, water, and other resources, which is why this is a period of decreased growth rate.
-Neonates lack teeth when they are first born, since they need to suckle from the mother's teat. And many mammals have a set of milk teeth without molars that will be replaced with permanent teeth with molars between weaning and puberty.
-When animals are first born their digestive tract is primed for digesting milk, not an adult diet. So as an animal goes from weaning to puberty, their digestive tract matures. The body changes in biochemistry, size, and microflora to help the body be able to process an adult diet.
-During this period, the infant will grow physically. The offspring will become larger relative to the original size.
-Females may need to integrate into a social system and establish a dominance rank
-Survival on their own (find food and shelter, avoid illness and predators, grow and mature)
-Overall hard to know
What are the costs and benefits of dispersal? When might these differ for females vs males?
Dispersal: juveniles moving to unfamiliar place by themselves
Benefits: Mother spreads her DNA, maybe increase chance of more grandchildren, exploration, no sibling competition, maybe more choices for mate, potential of finding more food or less predators
Costs: High mortality, low familiarity with area, loss of cooperation with relatives (for social species)
Benefits of staying: Mothers able to defend offspring, can help take care of grandchildren, less chance of mortality, stay within social group
Dispersal is thought of as a male trait, when that is not true.
Provide a practical, definition of puberty that could be applied in a non-captive study of one of your species.
Puberty is timed so the probability of a female successfully raising her first litter/offspring is high in a time frame that will create reproductive success--> female stoats (puberty before weaned and delayed implantation), squirrels (at one years old), humans (anthropocentric bias-->younger than humans believe we should be able to raise a child)
What determines when puberty will happen?
Body size: larger mammals usually hit puberty later.
Taxonomy: different species hit puberty at different times (female stoats vs similar species)
Habitat: Pheromones from urine (lab rats), ranking of baboons in social groups, amount of predation (more, means later)
Diet: more food, early puberty
Thermoregulatory ability: need to be able to control body temperature, needed to avoid heat stress from reproduction
What are possible benefits of a post-reproductive life?
The possible benefits of a post-reproductive life are that grandmothers can help care for their grandchildren, which will make them more likely to survive and grandmothers can protect their grandchildren, decreasing the potential of infanticide and increasing fertility rates. This is only really beneficial for social mammals.
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