ADAPTATION: Some animals and plants that evolve in only 
one place can be useful to researchers... we explain ... just 
ahead ... on Passport to Texas ... 

Passport to Texas from Texas Parks and Wildlife

Fisheries research biologist Dr. Garry Garrett, at the Heart 
of the Hills research Center in Kerrville, discovered a new 
fish species in the San Felipe Creek in Del Rio awhile 
back ... a species of gambusia that exists only in those 
waters. We started to wonder how that happens.

Typically what happens is, you have the ancestral version of the 
species throughout things like head springs, or spring areas, 
those are special isolated type environments. The temperature 
doesn't change; the water chemistry doesn't change because 
it's coming out of the ground. So you'll have animals that start 
specializing for that very stable environment. So certainly, in 
springs throughout the state we've often seen specialized 
animals. :24

Garrett says it's fascinating and challenging to figure out 
how the species specialized for living in the specific 
environment.

But the other real useful thing about understanding this is these 
are called indicator species. They've been around for thousands 
of years ... they've done just fine ... as biologists we monitor their 
status. When we see their status starting to go down, it tells us 
that the environment they're in is going down. Not just them. 
They're an indicator of a larger problem. So by watching these 
animals or plants they tell us in advance of things degrading 
that ultimately may affect humans. So they're kind of our early 
warning system. :27

That's our show ... For Texas Parks and Wildlife ... I'm 
Cecilia Nasti. 









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