Mammals Flashcards
What is the largest mammal?
Blue whale
What are the smallest mammals by body mass?
Etruscan Shrew
What are the smallest mammal by body size?
Bumblebee bat
What are features of mammals?
Mammary glands Hair Neocortex 3 middle ear bones Single lower jaw bone attached to skull Complex placenta
What are the three major groups of according to pattern of embryonic development?
Prototheria (monotremes)
Metatheria (marsupials)
Eutheria (placentals)
When did shrew like mammals first appear?
Triassic (225-195mya)
What reptiles did mammals evoke from?
Synapsid reptiles
When did mammals diverse further?
100 million years ago
How many mammal species are there?
5500
How many orders of mammals are there?
28
What are features of monotremes?
Primitive Egg laying 5 species Eg platypus One opening No nipples Spur on the hind leg
What are features of marsupials?
Give birth to poorly developed young
Young develop in the pouch
7 orders
Convergent evolution
What are features of the rodents?
1 pair of continuously growing incisors in each jaw
Many herbivorous but some omnivorous
Hugely dominates mammals (most)
What are features of Lagomorpha?
2 pairs of incisors in upper jaw
Eg rabbits and hares
What are features of Primates?
Distinctive skeletal structure, opposable thumb, large brain
Intelligent
What are features of Insectivores?
Small ground dwelling
Insectivorous
Eg mole shrew
What are features of Chiroptera?
Bats Webbed wings Large fruit bats and echo locating bats Disease vectors Highly diverse
What are features of carnivores?
Distinctive skull structure
Mostly meat eaters
Eg cat dog
Top predators
What are features of Ungulates?
Hoofed mammal
Perissodactyla eg horse rhino
Artiodactyla eg sheep
Herbivores
What are features of cetaceans?
Flippers
Aquatic
Eg whales dolphins
Echolocation and electroception
What are the importances of mammals?
Resource of milk hair skin Hunting Ecotourism Research animals Pets
What are negatives of mammals?
Pests
Disease
How many mammals are at risk of extinction?
25%
How many mammals have become extinct in last 500 years?
82
What is anisogamy?
Male or female (what gametes, how big and how much investment)
Why are female gametes more costly than males?
Eggs are bigger with larger energy store and produce less
What limits males breeding success?
Number of eggs able to be fertilised
What limits female breeding success?
Number of young raised
Why should males compete?
Eggs are a limited resource
How does gestation and lactation influences mating?
Females are constrained for lengthy development
Males can move on post copulation
When diet groups should males stick around in?
Carnivores- prey must be hunted, parental care needed, females solitary
What diet groups should males sleep around?
Herbivore- no parental care, female in groups
What is monogamy?
1 male
1 female
What is polygamy?
Multiple mating
What is polygyny?
1 male with many females
What is polyandry?
1 female with many males
What is the most common mating system in mammals?
Polygyny
What is a lek?
Group of males display to females who come to mate but not for resources
What are polygynandrous species?
Both sexes have multiple partners
Why would a mammal be solitary?
If can easily defend territory and resources
Too predators on have to hunt for themselves
Why would a mammal be semi sociality?
Mammals form temporary groups in certain conditions
For warmth
For reproduction
For protection
Why would a mammal be a sociality?
Eat but don’t get eaten
Individual breed independently
Why would mammals be communal breeders?
When stable groups occur, cooperation is advantageous eg.dogs hunting
Females breed and share offspring care
Low reproductive skew
Why would mammals be cooperative breeders?
If there’s breeding constraints Young or small females may stay in the group but not breed Non breeders may benefit from helping High reproductive skew Often only one female breeds
Which groups cooperatively breed?
Primates
Carnivores
Rodents
What happens in Eusociality?
In extreme cases non breeding females are sterile
Breeding females and workers show specialisation