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Lecture 1.2_Why Study Mammals?

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hello again ABS 470 online students

Professor Jared rathel here and I wanted

to start by thanking you for rejoining

me for lecture 1.2 so today I pose the

question why even bother studying

mammals and I'm going to make the

argument that although they are few in

number relative to like arthropods in

the system they can have highly

influential roles in structuring

ecological communities

were dependent upon mammals for food for

dairy for fiber for biomedical models next

if we ignore

the impacts of the mammals around us

I believe we do so at our own peril

and then lastly

we're mammals

so my biggest Hope For You in taking

this class is that you have a richer

understanding of homo sapiens of what we

so the first big idea that I want you to

gather from this lecture is that mammals

although their populations are

considerably smaller than other life

forms in the ecosystem like plants or

invertebrates they're going to form

these critical links in both terrestrial

and Aquatic systems like you can see

here so for example

African elephants by knocking over some

trees and then denuding others of leaves

and branches they're going to maintain

the grasslands within which they live by

keeping the trees at Bay and the

Savannah open

further elephants are going to eat

copious amounts of food and then uh drop

large bombs like you can see on the left

but that elephant feces is incredibly

nutrient Rich okay and they're going to

drop it sometimes kilometers tens of

kilometers from where they consumed it

so it's an important part in the cycling

of nutrients and there's been good

evidence that suggests when elephants

are present in African savannas as well

as in Southeast Asia they're going to

structure plant communities

similarly the presence of prairie dogs

right here in the desert Southwest is

associated with communities with higher

plant biodiversity

and then finally on the bottom right

here when whales massive whales die and

the carcasses sink to the sea floor

they're going to provide this ecological

succession this feeding Bonanza for rat

fish and hagfish and deep water sharks

so we're going to return to community

ecology specifically keystone species

like the sea otter here that's munching

on sea urchins keeping sea urchin

populations in check and maintaining the

health of those kelp forests we're going

to come back to sea otters and keystone

species in week six

beavers on the right here are considered

ecosystem Engineers so by slowing Rivers

down with their dams they create these

vital Wetlands they create habitat for

fish and Aquatic macroinvertebrates amphibians

amphibians

the insects uh they become really

abundant in all of those snags right

around the wetlands and so again we're

returning to a community ecology trust

me it's it's fun

um at a later date which brings us to

canis lupus here on the bottom left and

service olathes the gray wolf and the

elk of Yellowstone National Park and

your first discussion prompt

so gray wolves were part of the natural

ecosystem in Yellowstone National Park

but were deliberately exterminated uh

there as well as throughout much of the

uh contiguous 48 states in the 1920s you

guys probably know the story they were

trapped they were poisoned they would

pop where they go in and kill the pups

in the den

so my question to you is how would you

expect this extermination this removal

to affect ecosystem functions

so I want your initial discussion uh

response your comments to be concise

like peer-reviewed journals that's the

style we're aiming for they need to be

less than 300 words they need to

describe your conclusions present the

evidence or reasoning involved that

helped you get to that end point and

lastly I want a sentence or two

connecting your conclusions to content

in this course either from these

lectures or from your textbook readings

or your activities

and then you'll be randomly assigned a

colleague's discussion post and in less

than 200 words I want you to tell them

in a response what you liked what

they've done well uh feedback on what

they may have missed

um or maybe didn't elaborate well on

didn't Express well and then anything

you may have learned in Reading their post

post

so before you complete your initial post

don't forget to check out the resources

that are on canvas including an amazing

video it's been remastered it's called

how wolves change Rivers as well as the

famed or inFAMOUS Ripple and bashetta

it's often cited publication in

biological conservation so obviously

many of us are dependent upon mammals

for meat so think uh cattle

pigs lamb the Sami have their reindeer

or on the bottom right rabbits as well

as for dairy so again cows goats wool so

I think sheep and alpaca and lastly

Transportation right those Cowboys are

riding horses

if you've gone down into the Grand

Canyon or maybe have a super high you

may have caught a ride on a mule or had

a mule carry your stuff the Bedouin in

Arabia are riding on their camels the

Sami had been known to hook their

reindeer up to sleds so interestingly

it's hypothesized uh that goats which

were the first ungulate to be

domesticated it's thought dogs were the

first animal to be domesticated and

we'll talk about them on the next slide

but the goats were

the evidence suggests that goats were

domesticated about 10 000 years ago in

the zargos mountains and what is today

present-day Iran uh another interesting

factoid for you uh today an average

sized slaughterhouse in the United

so obviously uh mammals such as dogs and

cats ferrets my kids both have dwarf

hamsters they've clearly become our

companions right so we derive uh

pleasure from spending time uh with

these other species

an interesting study came out a few

years ago that measured oxytocin levels

and so uh when a human Companion Pets

his dog both the human and the dog get a

little jolt a little Spike of oxytocin

which is the feel-good pro-social hormone

hormone

so quite frankly I mean let's admit it

some dogs live such a Pampered existence

that you have to ask who is

domesticating who

okay so rodents have served as an

important biomedical research model for

over a century now because of their anatomical

anatomical

physiological and genetic similarity to

us to humans as well as their small size

the ease and cheapness of maintaining

rodent cultures as well as their short

life cycle and they produce lots of

young so early on researchers were able

to select and breed for certain lines

that Express traits associated with disease

disease

today it's relatively straightforward to

manipulate the mouse genome using crispr

to model diseases caused by gene mutation

mutation

so the mus musculus the house mouse

genome was first published in December

2002. and

that brings us to your second assignment

built into this lecture uh your first

primary literature summary

so we know that three-toed sloths carry

an incredible diversity of micro and

macro organisms in their coarse outer

hair so this is all algae here growing

in their hair along with a whole bunch

of microbes and protists and fungi

so conserving rain forests in Panama and

Costa Rica where these mall sloths are

distributed May in the long run be

greatly beneficial to us right

conserving these areas is going to help

us because they represent

repositories for these wondrous

compounds that can we can exploit

so they're uh in this study it talks

about 50 strains of fungi that were

cultured from a sloth back hair of which

20 had antibiotic properties

okay so I want you to to uh read this

primary literature article and remember

when reviewing primary literature for

abs 470 I want you to focus really on

that abstract the introduction as well

as the discussion sections please don't

get mired down in the methodologies okay

particularly in the uh statistics okay

again I want your summaries to be terse

and direct just like a peer-reviewed

journal just like your discussion posts

and I've got further directions that are

on canvas so next I want you to

recognize that mammals can be disease

reservoirs or even vectors so causing

disease transmitting diseases to us

bats are the leading cause of rabies in

the United States

researchers in China have posited that

it may have been a Pangolin a trafficked

Pangolin in a wet Market

that initially spread the novel

coronavirus covid-19 to humans

prions or Rogue proteins in infected

animal flesh so consuming prions can

cause rare but very serious

neurodegenerative disorders in humans

and then of course there are the rodents

so infected fleas living on ground

squirrels can Vector the plague deer

mice and cotton rats are going to shed

the deadly hantavirus in their urine and

[Music]

furthermore mammals can be incredibly

destructive as non-native invasive species

species

particularly on Islands so the Mongoose

which you see here on the left

um with the uh blood red uh mouth there

was introduced to the Hawaiian Islands in

1872. they purposefully brought Mongoose

over in an attempt to control rats

invasive rats and preserve or maximize

sugar cane yields you've probably heard

this story you may know it didn't work

out so well so rats are nocturnal

Mongoose are diurnal so instead of

eating rats the Mongoose primarily began

voraciously consuming uh the eggs of

ground nesting birds as well as the

birds themselves themselves as well as a

sea turtle eggs

on the uh right here

below right we see a feral cat that is

preying upon a native marsupial in

Australia so of course uh felids are

placental mammals they did not evolve uh

in Australia the only naturally

occurring placental is the dingo that

probably recently uh colonized Australia

from Indonesia so feral cats really have

no business being there and they have decimated

decimated

wallaby populations rabbits are another

huge issue in Australia

so important idea here to study

mammology today is to study conservation biology

biology

so of the

6500 species of modern mammals that have

been identified

approximately one in five are already

gone or are threatened or in danger in

serious decline

so you may have seen these

heart-wrenching photos on the left from

National Geographic this is Sudan the

last male Northern white rhinoceros last

male it's a sexually reproducing species

there's two females left I believe but

it essentially guarantees Extinction so

rhinos have been hammered by poaching

the horns are very valuable in Chinese

markets for the use in traditional medicines

medicines

which is particularly infuriating

because Rhino horn is made from the

super abundant protein keratin same

stuff that makes up your fingernails

on the right is the vaquita or the

little sea cow or the panda porpoise

which lives right south of us in the sea

of Cortez

this little guy is on the knife's edge

of Extinction so there's probably 30 or

less of them left so if you haven't seen

it already I would highly encourage you

to check out the movie Sea Of Shadows so

my colleague and friend Rue Mahoney was

the field director for this movie

Leonardo DiCaprio paid for it anyways

it's an eye-opening film also it's a

it's a tear-jerker and the final reason

why we should be studying mammals is

because we're mammals

so there are approximately 7.5 billion

of us on planet Earth that's billion

with a B demographers estimate that our

population will hit 9 billion and 2050

and top out at carrying capacity let's

hope between 11 and 13 billion and 2100.

so humans are now the fundamental

drivers of

eco-evolutionary processes on planet

Earth so much so that conservation biologists

biologists

geologists and demographers most of them

now agree that we've left the relatively

stable Epoch the Holocene within which

modern agriculture evolved and we've

entered a new epoch the age of humans

the anthropocene

so in short it is a really important

many thanks for listening to the lecture

and please reach out to me if you want to

exchange emails or a video conference

and discuss any of these Concepts in

Greater detail okay I'll see you next

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Lecture 1.2_Why Study Mammals?