APES Video Notes 3.2 - K-selected & r-selected species

Summary

In this educational video, Mr. Speeds explores the contrasting reproductive strategies of K-selected and r-selected species. K-selected species, like elephants, invest heavily in fewer offspring, ensuring their survival through long lives and parental care. In contrast, r-selected species, exemplified by spiders, produce numerous offspring with minimal care, relying on quantity for survival. The video discusses the biotic potential, the spectrum of reproductive strategies, and how r-selected species are more likely to become invasive due to their rapid reproduction rates. It also touches on how K-selected species are more vulnerable to environmental disturbances and invasive competition, potentially leading to extinction.

Takeaways

• 🐘 K-selected species focus on quality over quantity, investing heavily in the care of fewer offspring, like elephants.
• 🕷️ r-selected species prioritize quantity, producing many offspring with minimal parental care, exemplified by spiders.
• 🌱 Biotic potential is higher in r-selected species, indicating a higher maximum reproduction rate compared to K-selected species.
• 🌈 Most species fall somewhere on a spectrum between purely r-selected and K-selected, such as frogs and hares.
• 🌿 r-selected species are more likely to become invasive due to their rapid population growth and competition for resources.
• 🐘 K-selected species are more stable near their carrying capacity but are slower to recover from environmental disturbances.
• 🌋 The slow reproduction and development of K-selected species make them vulnerable to disturbances like diseases or invasive species.
• 🌱 r-selected species' rapid reproduction can outcompete K-selected species for resources in new ecosystems.
• 🦠 The slower generation time and smaller population size of K-selected species reduce their adaptability to environmental changes.
• 📉 K-selected species are at a higher risk of extinction due to their inability to adapt quickly to new conditions.

Q & A

What are the two reproductive strategies discussed in the script?

The two reproductive strategies discussed are K-selected and r-selected strategies. K-selected species focus on quality over quantity, investing heavily in fewer offspring, while r-selected species produce many offspring with little to no parental care.

What is an example of a K-selected species mentioned in the script?

An example of a K-selected species mentioned is the elephant, which takes good care of its few offspring and lives a long time.

What is an example of an r-selected species mentioned in the script?

An example of an r-selected species mentioned is the spider, which produces hundreds of offspring and leaves them to fend for themselves.

What is biotic potential and how does it differ between K-selected and r-selected species?

Biotic potential is the maximum reproduction rate of a population. It is much higher for r-selected species than for K-selected species, as r-selected species produce many offspring.

Why are r-selected species more likely to become invasive?

r-selected species are more likely to become invasive because their populations grow rapidly, allowing them to outcompete other species for resources when they move to a new ecosystem.

How does the lifespan of K-selected species affect their reproductive strategy?

K-selected species, having a longer lifespan, can afford to spend more time and energy on parenting, leading to fewer but better cared-for offspring.

What is the relationship between the reproductive strategies and the vulnerability to environmental disturbances?

K-selected species, with their slow reproductive rate, are more vulnerable to environmental disturbances because their populations take longer to recover. r-selected species, with their rapid reproduction, can recover more quickly from such disturbances.

Why are K-selected species less likely to adapt to changing environments?

K-selected species are less likely to adapt to changing environments due to their longer generation times, smaller population sizes, and less genetic diversity.

What is the significance of the term 'carrying capacity' in the context of K-selected species?

The carrying capacity refers to the maximum population size that an environment can sustain. K-selected species usually exist near their carrying capacity because their populations grow slowly and are relatively stable.

How does the script illustrate the spectrum of reproductive strategies between K-selected and r-selected species?

The script shows a spectrum by mentioning species like the frog and the hare, which produce a fair number of offspring and show some parental care, falling between the extremes of K-selected and r-selected strategies.

What science skill is being practiced at the end of the lesson?

The science skill being practiced is describing patterns or trends in data, specifically analyzing the relationship between zebra mussel and unionin mussel population density in the Hudson River.

Outlines

00:00

🐘 K-Selected Species: Quality Over Quantity

This paragraph discusses the concept of K-selected species, which are characterized by a 'quality over quantity' reproductive strategy. These species, such as elephants, have fewer offspring but invest significant time and energy in parenting. They typically live longer, reach sexual maturity later, and reproduce multiple times in their life. K-selected species have a lower biotic potential, leading to slower population growth. They are less likely to recover quickly from environmental disturbances and are more susceptible to invasive species due to their slow reproduction rate and long generation times.

05:01

🐜 r-Selected Species: Quantity Over Quality

The second paragraph focuses on r-selected species, which adopt a 'quantity over quality' approach to reproduction. These species, such as insects and fish, have short lifespans, reach sexual maturity quickly, and produce a large number of offspring with little to no parental care. This strategy results in high biotic potential and rapid population growth but also leads to variable population sizes. The paragraph also discusses the spectrum of reproductive strategies, noting that not all species are purely r-selected or K-selected, with some showing intermediate traits. The potential for r-selected species to become invasive is highlighted due to their rapid reproduction and ability to outcompete other species for resources.

Keywords

💡Reproductive Strategies

Reproductive strategies refer to the methods by which different species ensure the survival of their offspring and the continuation of their genetic lineage. In the video, two primary strategies are discussed: K-selected and r-selected species. These strategies are central to understanding how species adapt to their environments and ensure survival.

💡K-selected Species

K-selected species are those that invest heavily in a smaller number of offspring, providing extensive care and resources to increase their chances of survival. The video uses elephants as an example, highlighting how these species have a longer lifespan and take a quality-over-quantity approach to reproduction.

💡r-selected Species

r-selected species, conversely, produce a large number of offspring with minimal parental care, relying on the quantity of offspring to ensure some survive. Spiders are given as an example, where hundreds of offspring are left to fend for themselves, illustrating the quantity-over-quality approach.

💡Biotic Potential

Biotic potential is defined as the maximum reproduction rate of a population. The video explains that r-selected species have a higher biotic potential than K-selected species because they can produce many offspring in a short period, which contributes to rapid population growth.

💡Parental Care

Parental care refers to the behaviors exhibited by parents to provide for the needs of their offspring, increasing their survival chances. K-selected species typically show high levels of parental care, as mentioned in the video with the example of elephants, whereas r-selected species show minimal or no parental care.

💡Sexual Maturity

Sexual maturity is the age at which an organism is capable of reproducing. The video points out that K-selected species reach sexual maturity later in life, allowing them more time to invest in each offspring, while r-selected species reach sexual maturity quickly to maximize their reproductive potential.

💡Carrying Capacity

Carrying capacity is the maximum population size that an environment can sustain without being degraded. The video explains that K-selected species usually exist near their carrying capacity due to their slow population growth and stable populations.

💡Invasive Species

Invasive species are those that are not native to an ecosystem and can cause harm to the environment, economy, or human health. The video suggests that r-selected species are more likely to become invasive due to their rapid reproduction rates, which allow them to outcompete native species.

💡Environmental Disturbance

Environmental disturbance refers to any significant change in an environment that can affect its inhabitants. The video discusses how K-selected species are more vulnerable to disturbances like disease or forest fires because their populations take longer to recover.

💡Adaptability

Adaptability is the ability of a species to adjust to changes in its environment. The video explains that K-selected species are less adaptable due to their longer generation times and smaller population sizes, which result in less genetic diversity and a reduced capacity to evolve quickly.

💡Extinction

Extinction is the disappearance of a species from the Earth. The video concludes that K-selected species are more likely to go extinct due to their vulnerability to environmental changes and competition from invasive species.

Highlights

Introduction to two reproductive strategies: K-selected and r-selected species.

K-selected species focus on quality over quantity, investing in fewer offspring.

Examples of K-selected species include elephants, which live long and take good care of their young.

r-selected species produce many offspring with little parental care, hoping some will survive.

Spiders exemplify r-selected species, laying hundreds of eggs and leaving them to fend for themselves.

Objective to identify differences between K-selected and r-selected species.

Introduction of the term 'biotic potential', which is higher in r-selected species.

Most species fall somewhere on a spectrum between K-selected and r-selected strategies.

r-selected species are more likely to become invasive due to rapid population growth.

K-selected species are more likely to be negatively impacted by invasive species.

Reproductive strategies are suited to the organisms that use them, with both quality and quantity approaches working.

K-selected species are typically larger, longer-lived animals that reproduce fewer times.

r-selected species are generally smaller, shorter-lived organisms that reproduce quickly.

r-selected species have a high biotic potential, leading to rapid population growth.

A guide to basic traits of K-selected and r-selected species is provided.

Examples given of species that are in the middle of the K-selected and r-selected spectrum.

The impact of environmental disturbances on the recovery of K-selected species.

r-selected species' vulnerability to environmental changes and competition with invasive species.

K-selected species' slower adaptability to changing environments due to longer generation times.

The likelihood of K-selected species going extinct compared to r-selected species.

Practice skill of the day: Describing patterns or trends in data.

Data analysis exercise with a comparison of zebra mussels and union mussels in the Hudson River.

Transcripts

hey everybody its mr. speeds and today

we'll be covering two different

reproductive strategies that species

used to pass on their genes K selected

species use what I like to call quality

over quantity so they have just a few

offspring at a time but they take really

good care of them

and they're able to do this because they

live a long time and they can afford to

spend their energy in their time on

parenting so we have elephants here is a

great example on the other hand our

selected species take the quantity

approach to the question of how to pass

on the genes they have many many

offspring in the hopes that at least

some of them survive and they generally

live much shorter lives and often only

reproduce once so they can't really

afford to produce a few offspring and

take care of them they like to really

crank out the offspring as I like to say

and just hope that some of them survive

spiders here are a great example they're

gonna have hundreds and hundreds of

offspring they're gonna leave them to

fend for themselves and again they're

just going to hope that some of them

happen to survive our objective today is

to be able to identify the differences

between case lected and our selected

species and we have a lot of essential

knowledge today the first two are

basically everything you need to know

about our selected K selected species

and we have a new term here - no that's

biotic potential which is the maximum

reproduction rate of a population this

is going to be much higher for our

selected than it is for K selected

species and then we have to know that

not all species are perfectly are

selected or perfectly k selected so with

most classification systems in science

there's a spectrum so we'll talk about

how it's not just buying areas such as

one or the other and then finally we'll

talk about why our selected species are

more likely to become invasives and why

K selected species are more likely to be

negative negatively impacted by invasive

species and then the science skill that

we'll be practicing at the end of the

lesson today is to be describing the

patterns or trends in data so as I

mentioned in the intro we have the

reproductive strategies here R and K

selected and they sort of represent the

quantity versus quality approach and so

before we talk about the characteristics

we need to review that these are both

reproductive

strategies or approaches that different

species take to passing on their genes

so all species pass on their genes to

offspring it's basically the driving

force behind all of life and these are

just two different approaches to

accomplish that goal

so they both work and they're both

suited to the organisms that use them

and again we want to think of them as

strategies and focusing on either

quality or quantity so K selected

species here take the quality approach

they're typically larger longer lived

animals like large mammals and they only

have a few offspring at a time but they

take really good care of them so because

they live longer they take longer to

reach sexual maturity but they also

usually have the opportunity to

reproduce many times over their lifespan

since they only have a few organisms or

a few offspring at a time they invest a

lot of energy in them they get them food

they keep them warm and they might even

fight off predators because of this

though they have a lower biotic

potential or maximum reproductive rate

which means they're going to exhibit

slower population growth because it

takes a long time for them to give birth

and raise their offspring their

populations just can't grow as fast now

this can be a problem if there's an

environmental disturbance like a disease

or an invasive species because their

populations just take so long to recover

back to that initial size our selected

species on the other hand are going to

take the quantity approach so they're

generally smaller shorter-lived

organisms like insects fish and plants

and they often don't live enough to

reproduce numerous times so they've

really got to make that one-shot count

because they don't live long they reach

sexual maturity very quickly and they

produce many offspring at one time they

invest their energy in the production of

this large number of offspring but then

they invest little to no energy in

caring for them so often there's no

parental care at all since they don't

care for them they need to have a lot of

offspring in order to ensure that at

least some of them survive so they have

a very high biotic potential or maximum

reproductive rate however this

reproductive rate can also make them

more likely to become invasive species

because their populations grow so

rapidly they often outcome

Peet's lower case elected species for

reap resources like food or water so

here's a quick guide of the basic traits

for both case elected in our selected

species and again think of K selected

species is kind of taking their time

slow and steady wins the race they live

a long time so it takes them a long time

to reach sexual maturity and this also

means that they have to protect and care

for their offspring for a while as those

offspring grow and develop because their

populations grow slowly though they're

usually relatively stable they exist

near their carrying capacity or their

maximum population size our selected

species are basically the opposite they

live short lifespans they reach sexual

maturity very quickly and they reproduce

many offspring they also invest their

energy more in the production of

offspring rather than caring for them so

it takes a lot of energy for a mother

spider or fish to produce thousands and

thousands of eggs and then they don't

invest that energy and caring for them

so this leads to them having very fast

population growth but very variable

population sizes since they're subject

to kind of dramatic increases or

decreases so it's important to remember

that not every organism is perfectly

k-selected or are selected we can see

here two extreme examples of a highly K

selected organism the chimp or an Haley

are selected moister but you'll notice

here there's many species that are

somewhere in the middle like the Frog

and the hare so the frog and the hare

going to produce a fair number of

offspring compared to the chimp but

they're also going to show some parental

care compared to the oyster so not every

single organism fits perfectly into our

selector K selected it is kind of a

spectrum so here we have the mother hare

who is going to provide quite a bit of

care to her offspring they're going to

be somewhere in the range of 10 to 12 at

a time and frogs even though they may

have hundreds of offspring in a

reproductive cycle many frogs offer some

parental care such as this poison dart

frog here that's going to carry tadpoles

on her back so again it's a spectrum

these organisms aren't going to exhibit

the same kind of parental care that

pansy mother does having one baby chimp

every five years but they're also not

going to just leave their numerous

offspring to fend for themselves like

the oyster so now we're going to talk

about invasiveness and disturbance so

like I've said earlier both of these

reproductive strategies work to pass on

their genes or we wouldn't see so many

organisms in both groups but they do

have some disadvantages so the slow

reproductive rate or biotic potential of

k-selected species makes them slower to

repopulate after environmental change or

disturbance such as a forest fire or a

disease and then unfortunately there's

kind of a double whammy effect on

population recovery for the case

selected species since they're young are

born very vulnerable and usually unable

to care for themselves

the death of a parent often means the

death of their offspring as well so

that's more than just a one parent dying

that's impacting the population it's

also probably killing the offspring

their slow sexual maturity and their low

biotic potential also makes them more

vulnerable to being out competed for

limiting resources by highly competitive

rapidly reproducing invasive species so

as you may guess these invasives are

usually our selected species because

they repopulate so quickly when they

move to a new ecosystem they can

oftentimes out-compete the slower

reproducing k-selected species they're

slow population recovery also leads to K

selected species being less likely to

adapt to a changing environment this is

because they have longer generation

times and smaller population sizes so

there's less genetic diversity and as a

result their populations are less

adaptable they're less likely to have

beneficial mutations that allow them to

quickly evolve and adapt to new

environmental conditions so as a result

of all these factors K selected species

are far more likely to go extinct than

our selected species so today our skill

that we'll practice is concept

explanation and we want to be able to

identify one characteristic of an R

selected species that could increase the

likelihood of the our selected species

becoming a more successful invasive

species than a K selected species

so our second practice skill that we're

going to do here is data analysis so we

have a data table of zebra mussels and

Union in mussels and we want to be able

to describe the relationship between

zebra mussel and union in Mossel

population density in the Hudson River

alright everybody thanks for watching

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