Please help me out with this assignment. Thanks. Please read the “mate choice intro slides” and ” mate choice protocol” and complete the data spreadsheet and the mate choice worksheet. Treatment 1: ht

Please help me out with this assignment. Thanks. Please read the “mate choice intro slides” and ” mate choice protocol” and complete the data spreadsheet and the mate choice worksheet. Treatment 1: ht
Week 9 : Mate Choice in Female House Crickets Background Mate selection is the most studied animal preference in behavioral ecology. It is a prime tool for studying sexual selection. The exaggerated displays of peacocks, for example, are rooted in the evolution of mate preference . Typically in birds (and most species of sexually reproducing organisms), the female is selective/“choosy” and the male must compete for his reproductive success. This turns into a, sort of, coevolutionary contest between mal es and females where both are evolving in response to one another. Why are females the choosy of the two sexes? Females are the egg bearers. Eggs are large and food -rich, so they are much more costly to produce than sperm. Having different sized gamet es is referred to as anisogamous sex. Anisogamy also results in females having greater parental investment (parental care) towards their offspring after birth , than males. Females are limited by how often they can breed so t hey will benefit the most if t hey dedicate their energy to the success of their young. Males, on the other hand, benefit more from investing their energy into mating with more females — if they will choose him . So, what benefits do females gain from being selective about their mate choice? Choosing a healthy, s trong, large male, that is capable in combat would not only offer protection from predators to the female but will also provide her with the best genes fo r her offspring. In elephant seals, for example, as little as 5/180 competing males were responsible for 48 -92% of matings with 470 females. These males are the strongest and most capable of defending the ir territory . They can outcompete lesser males. Keep in mind that females are not always the choosy ones . When males provide the bulk of parental care, the roles reverse, and males become the choosy sex . Some examples of these organisms are seahorses and pipefish. There are also animals that exhibit mutual selection. Examples of these are grebes, gulls and albatross. In these species, both parents are involved in raising the offspring. Lab Intro In our previous cricket lab, we focused on studying intrasexual selection (male -male competition) between 2 male crickets. We looked at two hypotheses to help us predict the outcome of our experiments — Asymmetry of Value and the Resource Holding Potential. This week we will be studying intersexual selection (female choice) between house crickets — wh at characteristics and behaviors exhibited by the male cricket do females seem to prefer? In this lab exercise you will investigate two possible causes for a female cricket mate preference. The first (good resources) involves a history of prior investmen t in a territory by a male. This will be set up in a similar way to the asymmetry of value trial, except with an added female. The second (good genes) involves only present differences between male mate options. This will be set up in the same way as th e resource holding potential trial, but also with an added femal e. The experimental trials are manipulated so that the size of each opponent is varied, as well as their history of prior investment in the resource territory. You will determine which, if any, of the two listed causes for mate selection apply to house crickets. Cricket Behavior s In this lab we are going to strictly focus on dominant house cricket behaviors. When deciding if a behavior is dominant, consider who initiated it and who is in pur suit. Refresh your memory on the behaviors listed below. Keep in mind that mounting is strictly done by females and only when they ha ve selected their mate. Antenna tap: Crickets move their antennae and one may “tap” another. For dominant behavior, who tapped first? Body Raise: This is very distinct and can be a form of dominant behavior towards other males as well as a way to welcome a female for mating. Leg kick: Crickets may kick with one or both legs as another cricket walks behind. This is not the same as a jump. Head butt: When a cricket hits another with its head. Chase: One cricket pursues another. Shudder : The cricket quickly moves its wings as if to sing but only a flapping sound is made. Sing: Aka the cricket chirp. Crawl -over: One cricket will crawl over the other. Mount: The female mounts the male in order to copulate . Cricket Sexual Differentiation Large and small male crickets should be easily differentiable. To help you tell them apart, you may want to pay attention to features such as color variation, antenna lengths, wing length etc . On the last page of this document, you will find the first frame of each trial with small/large/female crickets identified. Male and female crickets can be differenti ated by the obvious presence of an ovipositor in females. The ovipositor is the long tubular structure at the back of the abdomen. It is used to deposit eggs into the ground/substrate. Careful not to confuse the wings of a male with the ovipositor of a f emale. Here is a picture of a female cricket: Data Collectio n: Treatment # Large Small 1 Owner Intruder 2 Intruder Owner 3 Intruder Intruder You will watch a series of videos on 3 experimental treatments. Above is a table that describes the cricket conditions of each treatment. Owner crickets were placed in their containers >24hrs prior to the start of the experiment. Females and intruder cr ickets were placed into the container 1 min prior to the start of each trial . Each trial is 9min long, and trial numbers are placed under the container. As you watch the video s, u se the provided excel sheet to help you gather your data. Pay attention to how the two male crickets interact, but also how they interact with the female and how the female interacts with them. Take note of which dominant behaviors you observe and who they are directed towards. Transfer the data to your worksheet and answer the questions about mate selection. Females: red circle Large males: yellow box Small males: no outline
Please help me out with this assignment. Thanks. Please read the “mate choice intro slides” and ” mate choice protocol” and complete the data spreadsheet and the mate choice worksheet. Treatment 1: ht
Mate selection • Most studied preference in behavioral ecology • Prime tool for studying sexual selection • The chooser and the chosen → coevolution between male and female Greater kudu Peacock Choosy Females • Females are usually the “choosy” sex… WHY? • Anisogamy vs Isogamy: • Gamete Size • Females produce large, immobile, food -rich gametes = eggs COSTLY • Males produce tiny, mobile, self -propelled DNA = sperm • Parental Care • Should males to invest? • Reproductive potential… Fig. 7.2 Parker et al. (1972) proposed that anisogamy evolved from isogamy by disruptive selection for two gamete sizes: large gametes with food reserves (eggs) and small gametes (sperm) which parasitize the investment of the large gametes Maximum # of offspring produced during lifetime Species Male Female Elephant seal 100 8 Red deer 24 14 Man 888 69 Kittiwake gull 26 28 Table 7.1 In polygamous or promiscuous species some males have a much higher potential reproductive rate than females Why be choosy? • Males compete for the female’s investment • Females choose males based on: • Best resources • Good genes Choosy Males • When would we expect to see this? • Males that provide the bulk of parental care Mutual Selection • When would we expect to see this? • Both parents involved in raising offspring • Sea birds House Crickets: Courting and Reproduction What do we know: – male crickets call to attract females – females can estimate the male’s size by the frequency of the call …chirp chirp … .. ….. … ………. .. chirp.. -female mounts the male (chooses!) To d a y : A s s e s s i n g F e m a l e P r e f e r e n c e i n m a l e House Crickets Treatment 1: Large Owner vs. Small Intruder Large: territory, size advantage Small: no territory, no size advantage Treatment 2: Large Intruder vs. Small Owner Large: no territory, size advantage Small: territory, no size advantage Treatment 3: Large Intruder vs. Small Intruder Large: no territory, size advantage Small: no territory, no size advantage House Crickets: Anatomy -females are typically larger than males -females have an OVIPOSITOR -don’t confuse for male wing tips MALE FEMALE Cricket Behaviors – dominant only! • Antenna Tap • Body Raise • Leg Kick • Head Butt • Chase • Shudder • Sing/Chirp • Crawl Over • Mount (females only) Example: Small Male Female Large Male