Ask a question related to this topic in the comment section below. In elephant seals, the alpha male dominates the mating within the group. This is because they often live in unstable environments where the slightest disturbance can wipe out their population. : A look at the (glaring) problems – Eco-intelligent, Longer gestation periods and give birth to one or two offspring at a time. Image credit: “Mike” Michael L. Baird https://www.flickr.com/photos/mikebaird/5397483362. The r/k selection theory explains whether a species chooses to be a k-strategist or an r-strategist. In some species, including some fish, crustaceans, mollusks, and other invertebrates, there are environmental (water temperature, length of daylight) or biological (pheromones) cues that cause males and females to release gametes at the same time.  In this situation, males and females are often not interacting with each other as individuals, but massed together so that all sperm and all eggs are in the same location. By Christian Fischer, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7344145, Like many bird species, hummingbirds provide food to their hatchling until the young birds are ready to leave the nest. I agree, it’s a useful way to introduce kids to the topic but it’s worth making a note of how things have moved on. 2. Examples of traits which typically confer first male advantage include: Examples of traits which typically confer second male advantage include: The genitalia of the male Callosobruchus analis beetle is covered in spines from base to tip; the spines facilitate removal of sperm deposited in the female’s reproductive tract by previous males. Image credit: By United States National Park Service – Tallgrass Prairie National Preserve, Public Domain, https://commons.wikimedia.org/w/index.php?curid=3260038. Male and female zebrafinch. Image credit: Lindsey Kramer/U.S. Low infant mortality: More often than not, they grow into adulthood and grow old, and this is when they are most likely to die a natural death. This video gives a brief overview of the implications of the good genes hypothesis and sexual selection in humans: Instead of (or in addition to) competing directly with each other to have the opportunity to mate with a female, males can also compete for fertilization of a female’s eggs after mating has already occurred! If a female mates with a male of poor genetic quality, and her offspring don’t survive as a result, she has wasted a lot of energy and resources and ended up with nothing. ( Log Out /  They lie in a zone where their chances of survival remain the same throughout their lifespan. The video below provides a quick overview of animal mating systems: Mating systems are influenced by competition for mates, and competition for mates is influenced by mating system. Except in the case of sexual (true) monogamy, there is always competition for fertilization. Ecologically, seahorses live in habitats with widely distributed resources, which means that the seahorse population is spread out and spread thin. R-strategists “live” near the line of exponential growth r. These organisms are nowhere near the carrying capacity, and can therefore afford to grow their population. Polygamy refers to either one male mating with multiple females or one female mates with many males. When one male mating with multiple females, called polygyny (“many females”), the female takes responsibility for most of the parental care as the single male is not capable of providing care to that many offspring. Normally, human reproduction begins when an egg cell is ‘reprogramed’ as a result of fertilization by a sperm cell. Typical K-selected organisms are elephants, and humans. Cauliflower coral broadcast spawning. Image credit: W. H. CalvinCC BY-SA 4.0, https://en.wikipedia.org/w/index.php?curid=50736326. A common example is the bright colors of many flowers . Their population has reached a specific size, and any uncontrolled growth will result in the death of the entire population. The female benefits by mating with a genetically fit male at the cost of having no male help care for the offspring. Change ), You are commenting using your Twitter account. Climate-induced rural–urban migration is a profound concern, and Dhaka’s political leaders have embraced technology-based innovation as one solution pathway. Table of Contents: 00:00 - Reproductive Adaptations 00:04 - What Are The 2 Types Of Reproduction? The vast majority of songbirds demonstrate social monogamy, where up to 40% of the offspring in a mating pair’s nest were not actually fathered by the male partner. Such organisms follow the Type II or B curve of survivorship. Asexual Reproduction Requires only one parent Offspring have 100% the same chromosomes as the parent. One question is why females should “care” about these showy male traits. Mogelgaard outlines four ways the links between climate change adaptation and reproductive health strategies need to be strengthened: in adaptation planning frameworks, tools and training, program design, and the evidence base for these connections.. The Dynamic Maturational Model of Attachment and Adaptation (DMM) is a transdisciplinary model describing the effect attachment relationships can have on human development and functioning. For example, in the yellow-rumped honeyguide (a bird) males defend beehives because the females feed on beewax. The r/k selection theory proposes to explain the reproduction strategies of species with respect to their environmental characteristics. Examples of direct male competition include: Male-male aggression in Mallard ducks. It is no surprise that these offspring are small in size; the need for numbers results in simpler, faster organization of the offspring. Reproductive strategies and energetic adaptations of polar zooplankton. The peacock’s tail is used on courtship displays to attract females. It’s not all just competition between males; females choose which males to mate with based on observing the male competition. Learn how your comment data is processed. I wrote this specifically because there are a lot of environmental science kids out there who find this concept confusing. Stalk-eyed flies have eyes at the end of long stalks, and they compete for mates by measuring the distance between their eyes. Fewer offspring are produced through this method, but their survival rate is higher than that for external fertilization. The r/k selection theory proposes to explain the reproduction strategies of species with respect to their environmental characteristics. )  How does that happen? Examples include breasts, showy tails and headpieces, and crazier traits like the length of the eye-stalks in stalk-eyed flies. But a male can mate with practically unlimited numbers of females with little loss of energy or resources, regardless of how successful those offspring may be. Fertilized eggs are retained inside the female, and the embryo receives nourishment from the mother’s blood through a placenta. Female choice (intersexual selection) and direct male competition (intrasexual selection) usually lead to selection for extremely “showy” traits that don’t appear to provide any benefit to the individual’s survival, and might even make it more likely for the animal to be eaten by a predator (think of the peacock’s tail – see below). Competition among males occurs whether species mate via internal or external fertilization. 1. that neither fit the k-, or r-strategist type of survival. This type of competition occurs when females mate only with a single male, typically the “winner” of the competition. Eco-intelligent™ is an environment blog in India. This video provides a great overview of sperm competition, but be aware that it erroneously refers to bonobos as having a polygymous mating system (they are promiscuous) and gorillas as being monogamous (they are polygynous): Three general mating systems, all involving innate and evolutionarily selected (as opposed to learned) behaviors, are seen in animal populations: monogamous, polygamous, and promiscuous. In addition to changes in a predatory strategy, examples of behavioral adaptations include changes in social patterns, communication methods, feeding habits and reproductive strategy. Because the male’s pouches, rather than the female’s eggs, are the limiting resource in reproduction, females compete with each other for access to males. Nothing else, we promise! The reproductive strategy of a species depends upon the interaction between intrinsic and extrinsic factors. ( Log Out /  Reproduction and Adaptation- Biology. Image credit:Özgür MülazımoÄŸlu/Flickr. What differs in different mating systems is whether the competition occurs before mating (direct male competition) or after mating (sperm competition). In class we’ll spend some time considering the relationships between mating system, when competition occurs, and the resulting effects on an individual’s behavior and/or appearance. They decided to develop as many offspring as possible, ensuring that at least a few will survive their harsh environment. https://en.wikipedia.org/wiki/R/K_selection_theory#Status, Is r/k selection theory still valid? The Type I curve, or A curve is typically followed by k-strategist organisms. What’s still more fascinating is that SCNT is not the only pathway to human cloning. Direct male competition often includes aggression (fighting) between males, but there are other forms as well. This site uses Akismet to reduce spam. The creation of National Adaptation Programs of Action (NAPAs) was a major initiative by the UN Framework on Convention … This process is poorly understood but suggests that males competition alone does not dictate success of that male sperm in fertilizing an egg. Proceedings of the National Academy of Sciences 104, 10921-1092. and Hotzy, C. & Arnqvist, G. 2009. Fish and Wildlife Service, https://www.flickr.com/photos/usfwspacific/5749767483, During sexual reproduction in toads, the male grasps the female from behind and externally fertilizes the eggs as they are deposited. Current Biology 19, 404-407. This occurs in some bony fish, some sharks, some lizards, some snakes, some vipers, and some invertebrate animals. Polyandry very rare because it involves sex role reversal, where females invest less in offspring while males invest more. Animal mating systems. Gen Comp Endocrinol. K strategist species show similar characteristics of reproduction like: Common examples of k-strategists species include humans, lions and whales. Male, female, and juvenile bonobos. The disadvantage for the female is that the male may abandon her – and her offspring – if he detects that she has mated with another male. Invertebrate Reproduction & Development: Vol. Once the babies hatch, they are on their own and must fend for themselves. They hatch at about 12 to 18 inches (31 to 46 cm) in length. This has to do with the rate of mortality (death) the a species faces at different stages of life. Water protects the eggs from drying out during development. Well, there is a reason for it. In large social groups, often all females are sexually receptive at the same time, meaning that a single male cannot prevent other males from mating with other females while he mates with one female. Learning Objectives. The statement above is a gross generalization, but biologically it tends to be true across most species that reproduce sexually, whether they reproduce with internal or external fertilization. In many instances, the embryo is isolated within the female, which limits predation on the young. Much more common is social monogamy, where two individuals partner together to rear their offspring, but also engage in “extra-pair copulations,” or matings with other individual (in human social parlance, we would call this “infidelity”). 36, No. Their populations rise and fall exponentially, depending on environmental factors. View all posts by Saurab Babu, This is nicely written but it’s a bit dated – most ecologists now don’t think in terms of r and K strategies, the field has really moved on – a nice summary of recent progress can be found here: https://en.wikipedia.org/wiki/R/K_selection_theory#Status. Reproductive traits of females have been shaped principally by natural selection for offspring production and survival, those of males by sexual selection for access to matings. There are many different types of adaptations in different species to maximize biological fitness, including parental investment, direct male competition, and indirect male competition. Social monogamy has both advantages and disadvantages for each partner. However, after the 1970’s, this theory received much scrutiny and criticism. Its purpose is to encourage the implementation of evidence-based interventions identified in various WHO sexual and reproductive health practice guides. They have high reproductive rates and numerous behavioural and physiological adaptations that assure them a fair fight in the struggle for survival. Wolff and Macdonald, TRENDS in Ecology and Evolution 2004 a time all encompassing theory to understand what meant. 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