lecture 13- soical behaviors studyguide .pdf

1 2 3 4 Title: Siblicide and Infanticide Siblicide: Refers to the act of one sibling killing another within the same brood or family group. It can occur in various species and can be classified as obligate (almost always happening) or facultative (occurring based on environmental conditions). Infant...

1 2 3 4 Title: Siblicide and Infanticide Siblicide: Refers to the act of one sibling killing another within the same brood or family group. It can occur in various species and can be classified as obligate (almost always happening) or facultative (occurring based on environmental conditions). Infanticide: This term refers to the killing of infants or young offspring, often by members of the same species. It can be perpetrated by both males and females and serves various evolutionary purposes 5 6 This concept describes the evolutionary conflict that arises from differences in optimal parental investment (PI) from the perspective of both parents and offspring. Parental investment refers to any investment made by a parent in an individual offspring that decreases the parent's ability to invest in other offspring, while simultaneously increasing the selected offspring's chance of survival. 7 The genetic relatedness between parents and offspring plays a crucial role in this conflict. While a parent shares 50% of its genes with each offspring and is equally related to all its offspring, each offspring is 100% related to itself but only shares 50% of genes with full siblings. This difference in genetic relatedness can lead to conflicts of interest between parents and offspring. 8 1. This slide distinguishes between obligate and facultative siblicide. Obligate siblicide occurs when one sibling consistently ends up being killed, while facultative siblicide may or may not occur depending on environmental conditions. 9 1. This section discusses examples of obligate siblicide in various bird species such as ospreys and golden eagles. It highlights how older siblings may kill younger ones, particularly in cases of asynchronous hatching where the hatching order establishes a hierarchy among chicks. 10 Further examples of obligate siblicide are provided, including species like masked boobies, brown boobies, and Nazca boobies. These birds exhibit behaviors where one chick typically kills its younger sibling, ensuring the dominance of the surviving chick. 11 12 1. The "insurance egg hypothesis" is introduced, suggesting that parents may lay multiple eggs as an insurance policy in case the first egg fails. The second egg, or B-chick, serves as a replacement for any siblings that do not hatch or die prematurely. 13 This slide discusses facultative siblicide, which occurs in response to interbrood or intrabrood conflicts. Examples include fur seals and blue-footed boobies, where environmental factors or sibling competition lead to the death of younger siblings. 14 1. Interbrood conflict among fur seals is highlighted, where pups born during years of poor conditions face increased mortality rates due to competition with older siblings. Similarly, intrabrood conflict among bluefooted boobies results in the younger chick receiving less food and facing aggression from the older sibling. 15 1. This slide summarizes the adaptive significance of sibling rivalry and siblicide. It suggests that parents manipulate hormone content in eggs to produce offspring with varying fighting abilities, ensuring resources are allocated to offspring with the best chance of reproducing. 16 1. This section explores the concept of infanticide, which involves the intentional killing of infants. It discusses the evolutionary implications of infanticide and the factors that may contribute to its prevalence within a species. 17 1. Examples of infanticide by males in various species, including lions, primates, and grizzly bears, are presented. This behavior often occurs when males take over new territories or prides, allowing them to eliminate potential rivals and increase their own reproductive success. 18 Examples of infanticide by males in various species, including lions, primates, and grizzly bears, are presented. This behavior often occurs when males take over new territories or prides, allowing them to eliminate potential rivals and increase their own reproductive success. Specific instances of infanticide events involving male leopards and chacma baboons are described. These examples illustrate how infanticide can occur in different contexts and contribute to the dynamics of reproductive competition within a species 19 his slide provides a link to a video and discusses the growth and development of baby colobus monkeys. It highlights research showing how infanticide pressure accelerates infant development in wild primates, such as colobus monkeys. 20 his slide provides a link to a video and discusses the growth and development of baby colobus monkeys. It highlights research showing how infanticide pressure accelerates infant development in wild primates, such as colobus monkeys. 21 22 This section explores infanticide perpetrated by females, which is less common but still observed in various species. It discusses how factors like food availability and territorial disputes may contribute to female infanticide. 23 Examples of female infanticide in species such as lagomorphs, carnivores, and rodents are provided. The slide highlights instances where females kill offspring of other females to gain access to resources like nesting sites or territories. A unique example of role reversal in wattled jacanas is discussed, where larger females defend territories against other females and kill offspring (male chicks) already present. The males then fertilize the offending females and care for their young. 1. This slide focuses on a unique case of infanticide perpetrated by females in wattled jacanas. These birds exhibit reverse sexual dimorphism, meaning females are larger than males. Females defend territories against other females and, if a female takes over a new territory, she kills the existing babies, which are typically male chicks. The males then fertilize the offending females and care for their young. 24 1. Brood parasitism involves the surreptitious addition of eggs to another female’s nest, either of the same species (intraspecific) or different species (interspecific). Parasitic birds benefit by increasing their number of offspring without the cost of parental care, while host birds raise parasite young at the expense of their own fitness. 25 This slide discusses facultative intraspecific brood parasitism, also known as eggdumping, where several females deposit eggs into a common nest. Examples include waterfowl, weavers, starlings, and marsh-nesting blackbirds. The wood duck is highlighted as a champion of egg-dumping. 26 Adoption, particularly in female ducks, can be beneficial as they commonly accept extra eggs laid in their nests and stray ducklings into their broods. This behavior may increase the odds of their own young surviving predation through the dilution effect, with little or no cost to the adoptive female. 27 This slide discusses occasional adoptions in colonially nesting gulls, where poorly fed chicks may leave their nests and join another brood. While this decision may benefit the chick, the adoptive parents on average lose some of their own young due to the adoption. The reasons behind this behavior are explored. 28 1. Gulls use an imperfect behavior when deciding which chick to feed, leading to occasional adoptions. Acceptance is based on confident begging behavior, but errors may occur, such as attacking or killing their own chick if they mistake it for a stranger. Despite the cost, occasional adoptions persist due to low selection pressure against them. 29 1. This slide introduces obligate brood parasites, including many species of birds like cuckoos, honeyguides, and cowbirds. These birds lay eggs in the nests of other birds and provide no parental care for their offspring. 2. 30 31 Reciprocal selection pressures between hosts and brood parasites give rise to novel forms of animal coloration, largely differing from those imposed by predators or mates. An arms race between hosts and parasites is illustrated, with examples of excellent mimicry of host eggs by the European cuckoo. 32 Host adaptations and mimicry strategies are discussed, including the optimal size of hosts and differences in incubation periods between parasites and hosts. Mimicry of predators by cuckoos, such as sparrowhawks, is also mentioned as a means to intimidate or distract host birds. 33 Viduine finches and their Estrildine hosts are discussed as examples of brood parasitism mimicry. Unlike cuckoos, Vidua nestlings do not eject other young from the nest, leading to multiple parasites in the same nest. Various mimicry adaptations are highlighted, including mouth markings and vocalizations. 34 This slide showcases the exact copy of the Purple Indigobird chick's mouth to that of its host, the Jameson's Firefinch. African Vidua finches are known for being hostspecific and exhibit remarkable mimicry to increase their chances of survival. 35 Images depict examples of egg removal by the Common Cuckoo and the Afrotropical Greater Honeyguide. These birds exploit the host parents' tendency to feed the largest young in a brood the most food, giving their own offspring an advantage in the competition for food. 36 37 1. This slide discusses historical and contemporary aspects of cowbirds, historically nomadic birds following buffalo herds. Today, cowbirds exploit resources provided by modern agriculture, leading to population growth and expanded distribution, impacting grassland and forest bird populations. 38 1.Cowbirds and Kirtland’s Warblers 1. This slide discusses the impact of brown-headed cowbirds on the endangered Kirtland’s Warblers. Kirtland’s Warblers have specific nesting requirements, nesting only on the ground near lower branches in large stands of young jack pines. Cowbird parasitism has exacerbated the endangered status of Kirtland’s Warblers, as they have not evolved defenses against cowbirds. Eradication programs implemented in the 1970s have helped mitigate this threat. 39 40 1. This slide examines why brown-headed cowbirds pose significant threats to several songbird populations compared to other brood parasites like cuckoos. Cowbirds are host generalists, meaning they parasitize a wide range of bird species without negative feedback to their own populations as one host species declines. Several bird species listed, including Cardinals, Song Sparrows, and Wood Thrushes, are vulnerable to cowbird parasitism. 41 1. Here, it's explained that cowbirds are host generalists, lacking negative feedback to their own populations as they parasitize a variety of host species. As one host species declines, cowbirds can switch to others, ensuring their survival. The slide includes references to articles discussing cowbird behavior and its impact on various bird populations. 42 1. This slide explores the evolutionary lag hypothesis, suggesting that hosts accept parasitic eggs because they have not yet evolved the ability to reject them. While there are benefits to rejecting a parasitic egg, rejection can be costly due to recognition errors, egg damage, and the potential destruction of nests by parasites. This hypothesis offers insights into why brood parasitism persists despite its costs. 43 1. The "mafia" hypothesis posits that hosts accept parasitism to avoid retaliation from parasites. This retaliation can involve the destruction of nests or eggs. Retaliation evolves when hosts condition their response to mafia parasites, who use depredation as a targeted response to rejection. Examples include the relationship between Great Spotted Cuckoos and European Magpies, as well as Brown-Headed Cowbirds and Warblers. 44 1. This slide raises the question of whether brood parasitism is pure parasitism. It presents evidence suggesting that when crows raise cuckoo chicks alongside their own, the survival rate of baby crows increases because the baby cuckoos defend the nest. Additionally, cuckoos secrete a noxious substance when threatened, deterring predators. This challenges the notion of brood parasitism as purely parasitic and explores the complexities of interspecies interactions. 45 ChatGPT ChatGPT The Parent-Offspring Conflict This slide likely delves into the evolutionary dynamics between parents and offspring, where conflicts arise due to differences in optimal parental investment. Offspring often demand more resources than parents are willing to provide, leading to a conflict of interest. The parent-offspring conflict theory, first proposed by Robert Trivers in 1974, describes this evolutionary tug-of-war over resources and investment. Offspring strive to maximize their own survival and reproduction, while parents seek to balance investment among multiple offspring to optimize their own reproductive success. Sibling Rivalry and Siblicide This slide probably explores the phenomenon of sibling rivalry and its extreme manifestation, siblicide, where one offspring kills another. Siblicide can be categorized into obligate, where one sibling almost always kills the other, and facultative, where it occurs depending on environmental conditions. Examples from various species, such as birds of prey like ospreys and golden eagles, may be discussed to illustrate this behavior. 46 Infanticide by Males and Females This slide likely examines the occurrence of infanticide, the killing of offspring, by both male and female members of certain animal species. The reasons behind infanticide can vary, including increasing mating opportunities, eliminating potential competitors, or redirecting parental care towards their own offspring. Examples may include lions, primates, bears, and birds where infanticide serves reproductive strategies or territorial dominance. Brood Parasitism: Types and Hypotheses This slide might discuss the different types of brood parasitism observed in nature, along with associated hypotheses explaining the persistence of this behavior. Types of brood parasitism may include obligate and facultative parasitism, as well as intraspecific and interspecific parasitism. Hypotheses could include the evolutionary lag hypothesis, which suggests that hosts have not yet evolved defenses against parasitic eggs, and the mafia hypothesis, which proposes that hosts accept parasitism to avoid retaliation from parasites. Examples from various bird species, such as cuckoos and cowbirds, may be provided to illustrate different aspects of brood parasitism. 46