1) Usually in animal behaviour we find the pattern that thefemales of a species are choosey about which male they want to matewith, while the males are just trying to mate. There are casesthough where the male of the species is choosier. What do you thinkthe adaptive benefit would be for each of the following scenarios?1) Female seahorses (see Figure 8.4 on page 220) show no preferencefor the males with which they mate, yet researchers found that themales of the species tend to choose larger females; b) In blackwidow spiders, researchers found that the males tend to preferwell-fed females over starving ones; c) Male jungle fowl mate withmore than one partner, and researchers have observed that malejungle fowl enhance the speed with which their sperm travel whenroosters inseminate attractive versus unattractive females.
2) Recognition is considered a critical basis for discriminatorybehaviours in animals. A study showed that host reed warblers(Acrocephalus scirpaceus) of an evicting parasite, the commoncuckoo (Cuculus canorus), avoided the costs of prolonged care forunrelated young by deserting the cuckoo chick before it fledged.Desertion was not based on specific recognition of the parasitebecause hosts accept any chick cross-fostered into their nests.Researchers theorized that reed warblers had evolved a way to avoidhelping a parasite, namely a time limit on parental care for abrood. To test this theory, researchers set up experiments so thatthe period of parental care needed for the young to fledge wasextended beyond normal fledging times. Younger and older chickswere transferred between nests to manipulate the natural period ofcare required. What did the researchers expect as a result if theirtime limit hypothesis was correct? What advantage would the reedwarblers have if they used the time limit hypothesis rather thanlearning what kind of nestling to care for and which ones toreject?
1) Usually in animal behaviour we find the pattern that thefemales of a species are choosey about which male they want to matewith, while the males are just trying to mate. There are casesthough where the male of the species is choosier. What do you thinkthe adaptive benefit would be for each of the following scenarios?1) Female seahorses (see Figure 8.4 on page 220) show no preferencefor the males with which they mate, yet researchers found that themales of the species tend to choose larger females; b) In blackwidow spiders, researchers found that the males tend to preferwell-fed females over starving ones; c) Male jungle fowl mate withmore than one partner, and researchers have observed that malejungle fowl enhance the speed with which their sperm travel whenroosters inseminate attractive versus unattractive females.
2) Recognition is considered a critical basis for discriminatorybehaviours in animals. A study showed that host reed warblers(Acrocephalus scirpaceus) of an evicting parasite, the commoncuckoo (Cuculus canorus), avoided the costs of prolonged care forunrelated young by deserting the cuckoo chick before it fledged.Desertion was not based on specific recognition of the parasitebecause hosts accept any chick cross-fostered into their nests.Researchers theorized that reed warblers had evolved a way to avoidhelping a parasite, namely a time limit on parental care for abrood. To test this theory, researchers set up experiments so thatthe period of parental care needed for the young to fledge wasextended beyond normal fledging times. Younger and older chickswere transferred between nests to manipulate the natural period ofcare required. What did the researchers expect as a result if theirtime limit hypothesis was correct? What advantage would the reedwarblers have if they used the time limit hypothesis rather thanlearning what kind of nestling to care for and which ones toreject?
