To best understand the present, we must better understand our past.  This concept applies to many facets of life including natural history.  Today we will take a look at the past.   

Researchers often explore how a species of interest evolved to its current form or sometimes to understand what caused its demise. We will review one of each today from papers recently published.

First, let’s discuss frogs’ teeth.  Teeth are probably not something you think about when you consider the frog.  Until this post, I didn’t think frogs had teeth at all!  However, some have pairs of fang-like teeth.   Others have rows of tiny teeth and still others are completely toothless.  Out of more than 7,000 frog species, only one has a set of true upper and lower dentures. 

A team at the Florida Museum of Natural History studied every genus of amphibians to discover that frogs have lost their teeth at least 20 times during their evolution.  Over millions of years, they may have re-introduced teeth at some points and lost them again.  Their diet likely influenced whether teeth were needed or not.  When frogs consume mostly tiny insects, their specialized tongue seems to be sufficient. 

You can learn more at the Museum’s webpage:  https://www.floridamuseum.ufl.edu/science/frogs-have-lost-teeth-more-than-20-times/

Or read the scientific publication here:  https://doi.org/10.7554/eLife.66926

@FloridaMuseum  @danpaluh

 

Next, we will step further back in time.  Really far back.  Let’s explore the Early Triassic period.  That’s approximately 250 million years ago.  During this time, the Antarctic had a temperate climate. 

The first animals to arrive in Antarctica were amphibians and reptiles. 

Recently, a team from the University of Washington, pressing on with research at home because of the pandemic, recognized fossils of Micropholis stowi, a salamander-sized amphibian from this early period. This particular fossil originated in Antarctica and was gathered during a 2017-2018 collection trip to the Transantarctic Mountains.    Fossil records on this continent are unusual.  Previously, the species had only been found in South Africa. 

Who would have expected to find an amphibian on Antarctica?  You never know!

You can read more about the research here:  https://www.washington.edu/news/2021/05/21/pandemic-paleontology/

@UW   @Koskinonodon

Let’s start with some grounding facts:  Frogs are part of the Anura order of amphibians.  Anura means without a tail.  So, what about toads?  Yes, it includes them too.  Technically speaking, all toads are frogs, but not all frogs are toads.   

This is relevant because they share some of their winter survival Froghabits which we will see as we discuss the various overwintering tactics. 

There are different approaches to winter depending on the type of frog.   Aquatic frogs such as the American Bullfrog (Rana catesbeiana) and the Northern Leopard Frog (Rana pipiens)  live in and around rivers and ponds.  Therefore, it’s probably not surprising that they hibernate in the water.  However, unlike turtles who need little oxygen in this state, frogs need oxygen.  When winter approaches, they will sink to a deeper, oxygen-rich depth of the water then they will slow their metabolism down and wait out the season.   

Other species that live on land such as our locally ubiquitous Spring Peepers (Hyla crucifer) and Wood Frogs (Rana sylvatica) hibernate in leaf litter and other crevices.  They increase their concentration of glucose and sugar alcohols to preserve their organs much like antifreeze does in your car engine.  As a result, these frogs can freeze and still survive.  Ice crystals can be found in their bodies.  When warmer temperatures arrive, they will thaw out and the organs begin to function again.  

The American Toad (Bufo americanus), a land dweller and the only type of toad found in Maine, digs down in the soil to get below the frost line. The Fowler’s Toad (Anaxyrus fowleri), found in the Midwest, Mid-Atlantic, and other parts of New England, also borrows down.  In contrast, the Great Plains Toad (Anaxyrus cognatus), found in the plains states and up into Canada, may use dormant rodent burrows for its winter domicile.  

Of course, not all frogs need a winter survival strategy.  Many types live in areas where the temperature rarely dips below 32°.  

Lastly, the frogs’ adaptation strategies are not foolproof.  Some can resist lower temperatures than others, so our increasingly erratic shifts in weather and climate make it difficult for them to survive.  

This is a problem. Did you know that frogs are an indicator species?  What this means is that they provide an early indication of the declining health of an environment.  Because of their permeable skin, they are highly sensitive to changes in pollution, bacteria, algae, UV, and pH levels.  The news isn’t good, most frog species have been on a severe decline for the past several decades.

Without the frogs, we will invariably have more mosquitoes and other pesky bugs.  Plus, they are a major component of the food chain for birds, fish, snakes, and some mammals.  Let’s work towards a better outcome for our frog friends, and ultimately for ourselves.

Sources:

Frogs in winter — https://www.scientificamerican.com/article/how-do-frogs-survive-wint/

More about the Great Plain’s Toad — http://fieldguide.mt.gov/speciesDetail.aspx?elcode=AAABB01050

Every year, right about this time, I start getting excited about the prospects of exploring vernal pools.  I hope you do too.

What’s a vernal pool?  These are the fairly shallow, temporary pools of water you find during the spring season, usually in forested areas. The pool returns each year, varying in size, depending on the quantity of snowmelt and rainfall.  During droughts, they may not return at all — and that’s a problem.  

What makes vernal pools special is that they are the breeding ground for certain species, including some that have no alternative options.  These include certain types of wood frogs, salamanders, and, my favorite, fairy shrimp, to name just a few. 

Why don’t these species chose to breed in permanent sites such as ponds and streams?  There are some positive trade-offs to what seems like a precarious location.  For example, vernal pools are safer than other bodies of water because there are no fish to eat the eggs or larvae.  Also, there may be specific plants growing close by to where the pools form, providing food and cover from predators.

What shall I look for in the ponds?  First, look for the sunny patch on the pond.  Then see if you can spot some tiny (about 1 inch long) lobster-like creature.  In some cases, they may be seen swimming on their backs, with their legs up toward the sun.  You’ll want to find these guys early in the season because they cannot survive water temperatures above 70℉.  Interestingly, however, their eggs can and will survive the heat.  On the other hand, the eggs will survive the drying out of the pond and will hatch the next time conditions seem right.

In mid to late spring, you will find egg masses in the pond. By late spring and early summer, you may find larval salamanders and tadpole frogs.  You may also discover turtles (including some rare species), snakes, interesting plants, and possibly even some birds that are specifically attracted to the area.

Can I find a vernal pond where I live?  Vernal pools occur in many states, including Missouri, Minnesota, California, Arizona, New Jersey, and in all the New England states.  

For more information, check with your local Department of Environmental Protection or Audobon group.  They are likely to have additional details about the specifics of vernal pools in your state.   

Here are two sources that are particularly good:  https://mnfi.anr.msu.edu/abstracts/ecology/Vernal_Pool.pdf

https://www.wildlife.state.nh.us/nongame/documents/vernal-pool-manual.pdf

You don’t have to look very far to find something unexpected in nature.   Today we will explore two examples. 

Rebecca Brunner, a conversation ecologist and PhD candidate at the University of California, Berkeley, recently discovered that the glass frogs (Sachatamia orejuela) in Columbia and Ecuador were “waving” hello.  The male glass frog moves its hands and feet and bobs its head along with a vocal call in an attempt to attract a mate.

These frogs are found near waterfalls which are fairly loud.   They apparently evolved to include these visual displays to supplement the vocalizations which may not have always been loud enough to get the desired response.  This is a relatively rare behavior amongst frog species.

Check out Brunner’s Youtube video here:  https://youtu.be/U6prmVIyxXI

The frog movements may be subtle to humans but they work for them!

More unexpected nature:  The plant world is also full of surprises. 

We know that species evolve in response to stimuli in their environment, such as developing a toxin to deter animal grazing.  Taking it one step further, in November 2020, three scientists reported in the journal Current Biology, that plants can also evolve as a result of pressure from human harvesting activities.   

Fritillaria delavayi is usually a bright green wild plant that grows amongst the scree on the mountalns in southwest China.  It is frequently harvested as a traditional Chinese medicine.  Amazingly, some of the plants have responded to the pressure by changing their coloration to gray so that they blend in with the rocky ground, making the plants more difficult to find.  In fact, areas with the greatest harvesting activity also exhibited the greatest degree of color change.

Science News has a great overview and a nice side by side set of photos to compare the coloration.   Look here:  https://www.sciencenews.org/article/plant-camouflage-people-china-traditional-medicine-fritillaria