Ocotillo on the Boo Hoff trail, Santa Rosa Mountain wilderness

Biodiversity can be appreciated at multiple scales, from within a species and within populations (at a genetic level), to scales that encompass communities of a variety of species within a habitat or across landscapes of many habitats comprised of  interacting communities of organisms.  For most of us there is an understanding that higher biodiversity at each of these scales is a positive attribute, but why?

In part the answer is that with greater biodiversity there comes higher levels of redundancy. Communities with lower biodiversity are more fragile than those with higher biodiversity. Imagine a habitat with a single species of plant-eating insect and a single species of an insect-eating lizard. As long as there are just enough insects to sustain a healthy population of lizards, the there is a level of equilibrium. But, if a severe drought, or if a pandemic kills the insect, the lizard population starves. Or if a lizard-eating bird enters the community and reduces the lizard population, the insect population could increase to a level where the plant community is damaged by the insects and their voracious appetites. Either way the community collapses. However, if that community included multiple species of insects, and multiple species of lizards, that redundancy can buffer the community. The role of any one species can be filled by another and the dynamic equilibrium between predators, prey, and vegetation can be sustained.

James Estes studied a marine environment in the Aleutian archipelago that lacked biodiversity. There was a single predator species (sea otters), very few prey species (mostly sea urchins), and a single plant species (giant kelp). Sea otters ate the urchins, and the urchins ate the kelp. As long as the numbers of each were in balance (equilibrium) a dense kelp forest existed that acted as a nursery for a multitude of fish species. But then the local Orcas developed a taste for sea otter, decimating local otter populations. Without otters the urchin population exploded, and they ate all the kelp. There was no redundancy to compensate for the decline in otters; the community collapsed, and the critical fish nursery was lost.

Kevin Crooks studied coastal sage communities near San Diego. Coastal sage is generally a diverse community of plants, insects, lizards, songbirds, small seed and plant eating mammals (rodents), medium-sized omnivorous mammals and a few large predatory mammals (mountain lions, bobcats and coyotes). However, San Diego is a popular place for people to live, and the coastal sage community has been sacrificed for thousands of new homes to meet the needs of a burgeoning population of humans. Soon the coastal sage community was sliced and diced until there were just a few isolated natural habitat fragments left. Kevin's question was whether those habitat islands still retained the biodiversity of what once characterized this community. The first to go were the large predators; the big cats and the coyotes could not maintain populations in such small habitats. Then something curious happened. Without the larger predators around, the medium sized (meso-predators) mammal populations (skunks, raccoons, weasels, and opossums) exploded, and preyed upon the lizards, songbirds and small mammals to the point where the smaller creatures were no longer able to maintain populations. Excluding the top predators resulted in a “trophic cascade” and a loss of biodiversity.

Then there is genetic biodiversity at a species or population level. Darwin worried about this for his own family, even before there was a modern understanding of how genetics works. At that time, and for centuries before, European culture dictated that marriages occur within social classes and typically within a finite group of families with social and economic ties. Royal families throughout Europe intermarried to solidify strategic alliances. The result was an inordinate propensity of hemophilia and insanity. The Darwin and Wedgewood (famous for their fine china) families had similar ties of intermarriage. Darwin married his first cousin Emma Wedgewood. Darwin himself suffered in his middle and older ages from undiagnosed debilitating gastrointestinal distress that was shared by several of his cousins. Emma and Charles had ten children, seven of which survived to adulthood. Just three of his adult children had children of their own. Darwin and Emma had a long happy marriage full of love and respect, but he was guilt-ridden that their lack of genetic diversity had doomed their children, despite the fact that three of his sons were Knighted for their respective advancements in botany, astronomy and engineering. Had the Darwin-Wedgwood intermarriages continued Darwin's guilt would have likely been well-founded and his lineage may have had a short family tree. Perhaps because of his concerns, his children and grandchildren and great-great grandchildren found spouses outside of that close family circle, and there are now some 100 descendants of Charles Darwin. Today one of those great-great grandchildren, Sarah Darwin is a professor and botanist who has studied rare plants in the Galapagos Islands. Another, Christopher Darwin lives in Australia and works on his goal of halting the global mass extinction of species, and a third, Jos Barlow is a noted ecologist. Charles would be pleased.

I saw another example of the effects of genetic diversity on our community science climate change-effects survey yesterday. We were on the Boo Hoff trail, at the driest end of our survey gradient. What struck us all as curious was that of the ocotillo that dotted the hillsides along the trail, a few were leafing out, while most were still dormant. Ocotillo have adapted to dry desert conditions by leafing out after significant rainfall events, and if there is additional sufficient rain, flowering, fruiting and then dropping all their leaves and going dormant until the next rain happens. Under the right sequence of rain events they can repeat this sequence up to three times in a single year. While we did have a brief and scant rain shower about two weeks prior to our survey, most of the ocotillo were unconvinced that it was enough to risk putting precious resources into forming new leaves. But a few were convinced. Those were the risk takers, “betting” that more rain would come, and by getting a head start they would stand a better chance of completing their flowering and fruiting cycle before drought once again pushes all the ocotillo back into dormancy. If they are right, they will produce more seeds and have more potential to continue their genetic lineage. If they are wrong, they will have wasted those precious resources, and if the ensuing drought is particularly long, and hot they may not survive to reproduce again. Genetic diversity producing risk takers and conservative wait and see-ers. In an unpredictable desert climate one or the other, or both will win the survive and reproduce lottery.

Biodiversity at all scales is good.

A "Natural History Note" From UC California Naturalist's new lead scientist, Dr. Cameron Barrows.

Flat-tailed horned lizard (Phrynosoma mcallii ) sunning on a rock

We often associate spring with when nature renews itself. Flowers and baby animals are the icons of spring. Except if you are a lizard. Lizards do breed in spring and early summer; however, it takes about 60 days for those eggs to hatch. Those hatchling lizards will not emerge and greet their new world until mid-summer to early fall. Depending on the year and the availability of food, female lizards will lay anywhere from zero egg clutches (in years when there isn't enough food available produce energy-rich eggs) to one, two or three egg clutches (in years with plentiful food). Each clutch separated by about a month, the time it takes for the females to replenish their fat reserves sufficiently to provide the energy and nutrients to produce more eggs. Fall is (also) the time to celebrate nature's rebirth if you are a lizard lover.

Not all lizards lay eggs. Some, especially those at high elevations, give birth to live young. Putting your eggs in the ground when an early or late frost could kill them is not a good strategy. Keeping your growing embryos inside your body where you can move in and out of patches of warming sunlight makes much more sense. For those, typically lower elevation lizards that do lay eggs, the gravid female lizards excavate nest chambers where they deposit their eggs and where those eggs will incubate until they hatch. That process never ceases to amaze me. The mothers-to-be must dig a nest chamber that is deep enough to be not too hot or too cold, and humid enough, but not too humid (too humid might foster mold or bacteria that would kill the embryos) and not too dry (the embryos would desiccate), and she must select sites that will provide those optimal conditions for those 60 or so days before her eggs hatch. Researchers have found that lizard eggs that are incubated too warm will mature and hatch faster, but they will lack the mental acuity of those incubated cooler and slower. Mental acuity? Apparently, more time in the egg allows neurons to develop more fully. In this case it means the ability to show awareness of potential predators and then take appropriate evasive action. Being incubated too warmly means your chance of passing on your genes to the next generation is far less than those who experienced cooler-slower incubation.

My amazement does not stop there. Imagine when those eggs hatch. It will be totally dark, but they need to find their way to the surface. The mother will have back-filled the tunnel she excavated leading to her nest chamber – both to keep humidity in and so that predators do not find her eggs. In those 60 days of incubation, the tunnel to the egg chamber will have collapsed even further. Yet, despite having never-before exercised their arms and legs, the hatchlings will need to dig to the surface and be ready to both find food and avoid becoming food. Amazing beyond words.

Here in the Coachella Valley, the summer of 2020 broke the record for the number of days that the high temperatures exceeded 100 degrees F – over 150 days, five months straight of blistering heat. That was nearly three weeks more that the previous record. What does that mean for those lizard eggs that were laid before the onset of heat? If being incubated too hot results if fewer hatchlings or hatchlings less able to meet the challenges of life, what does that mean for the Coachella Valley fringe-toed lizards?

This past week the temperatures finally cooled just enough to go out on the sand dunes safely and see how those hatchlings were doing. It was a wet enough spring to have allowed the adult females to build the fat reserves to have multiple clutches; there should be plenty of hatchlings. Community Scientist Cathy Wiley (California Naturalist class of 2019) and I went out on the dunes yesterday. The numbers of hatchling fringe-toed lizards were under-whelming. There were a few, but the ratio of hatchlings to adults was 0.5 to 1. I would have predicted 2-4 to 1 based on the wet spring. The day before I had checked the somewhat cooler dune habitats along the Kim Nicol trail and found the hatchling to adult ratio to be 1.5 to 1, somewhat closer to my expectation. This is too preliminary to identify causes, but perhaps we are seeing the effects of climate change. If so, this is not good.

Perhaps even more interesting, Cathy and I found lots of hatchling flat-tailed horned lizards, and good numbers of hatchling shovel-nosed snakes. We saw the tracks of both (probably dozens of separate hatchling horned lizard tracks) and were able to follow those tracks and find the baby horned lizards on several occasions. So, these two species seemed to be doing well. What is the difference? I can only guess, but perhaps flat-tailed mothers dig deeper (cooler) nest chambers?

There is never any lack of questions to pursue, always another piece of the puzzle to fit into place.

Go outside, tip your hat to a lizard, and be safe.

A colleague recently posed a rhetorical question, “Why do we need naturalists?” It gets to the question, “Why is the UC California Naturalist program important?” a question we don't often ask ourselves or contemplate in part because its value is such an integral part of who we are, it's ingrained and deeply-held, and we don't often stop to fully articulate an answer. While it is easy to describe what we do and why that is important to us and the nearly 4000 certified California Naturalists in our community, it is a much bigger challenge to present a cogent and memorable case that resonates with those outside of the field.

As a starting point, here are just a few examples, ranging from the pragmatic to the personal, of why we need California Naturalists.

Without the California Naturalists . . .

• fewer people, in a new era of extinction, would understand the value of (intrinsic or otherwise) of our state's threatened biodiversity
• fewer observations, data points and discoveries would be made of the natural world to help us measure our impacts on it.
• fewer people would have the opportunity to build a positive identity with science or recognize the value of more holistic ways of thinking such as traditional ecological knowledge.
• fewer people would engage in environmental stewardship behaviors ranging from resource conservation to building resilience among vulnerable communities.
• fewer people would access, experience, and value the unique cultural and natural resources that our state's public lands offer.
• fewer people would volunteer to support the hundreds of organizations managing public or conservation areas, educating the public, and monitoring environmental change.  
• fewer people would experience the joy, inspiration, discovery, camaraderie, and transformational learning that comes from taking a California Naturalist course.  
• fewer people would enjoy the benefits of improved personal health and well-being derived from spending time in nature.
• fewer people would recognize the importance of the natural capital that our environment represents in the form of ecosystem services that sustain our economy and our spirits.
• fewer people would recognize the need to build the resilience necessary for our communities and ecosystems to not only survive but thrive in an changing climate.

We need naturalists for all these reasons and more.

There is a saying. “The frog in the well will never know the immensity of the sky.” The UC California Naturalist program broadens our horizons. It inspires people to engage in stewardship behaviors that make our home a better place to live and our communities more resilient to changes we face. We need California Naturalists because just as these challenges are the result of the cumulative impact of millions of people their solutions exist in the cumulative actions of people. More than anything else, the UC California Naturalist program builds a shared understanding, capacity, identity, and values that help us move in the same direction toward a common goal.

Warning: this blog post discusses some creepy crawlies. If you have an insect or arachnid phobia you may want to skip this post.

It's spooky season, and we're getting in the spirit with some natural history, of course! Unless you're one of the entomologists with our sister program UC IPM, most people, including CalNat staff, find an aversion to least one type of invertebrate. Despite their their aversion inducing qualities, as naturalists we know that each creature fills an important niche within its ecosystem. Even the creepy ones. This Halloween we thought it would be fun to share the natural history of insects that give CalNat staff goose bumps.

Up first: moths.  

Western Poplar Sphinx from California Naturalist Steve Kerr.

The flapping of moth wings, which in some parts of the world can reach lengths of nearly a foot, can be frightening as the nocturnal species make their way towards a bright light in the night time. Once the comfort of daylight arrives, you may better see the diurnal species, busy fulfilling their ecological niches. Though some can be difficult to spot, as they amazingly camouflage or even mimic other animals. Moth species outnumber the more popular butterfly over 10 to 1. With thousands of moth species in North America, they serve multiple vital roles! Before metamorphosing into adults, moth caterpillars are an important food source for other animals. Adult moths are important pollinators for plants. Their fuzzy wings and bodies are excellent at capturing pollen.

Second: the Jerusalem cricket AKA “niñas de la tierra” (children of the earth), sand crickets, or potato bugs. 

Jerusalem cricket from California Naturalist staff Brook Gamble.

The large 2-inch long size and human-like head of these crickets alone can give you the shivers. You can get way too up close and personal with these identification marks when one shows up every so often in your garden or dead on a sidewalk. Though for a curious naturalist, getting up close and personal offers a chance to make observations you normally wouldn't have. Their unique colors and patterns can't be missed. These crickets feed and tunnel underground during the night, helping to control insects as a part of their diet alongside roots and tubers. This tunneling can be really beneficial by providing aeration and nutrient cycling to the soil. They're a delicious snack for nocturnal animals like bats, coyotes, badgers, birds, skunks, and foxes.

Next: spiders!  

Funnel weaver spider from California Naturalist staff Eliot Freutel.

There's more that unites us instead of divides us, and that includes fear of spiders. Up to about 6% of the global population has arachnophobia. Out of about 45,000 species of spiders, 200 have any venom that could cause harm to humans. Just like the humans that fear them, spiders are amazingly diverse. From size, to web shape and texture, jumping abilities, prey, colors, number of eyes, habitat, and more, they serve an important role in the web of life. It's thought that on one acre of woodland, a spider can eat 80 pounds of insects in just one year. Not all spiders use webs to catch their prey; though all spiders have the ability to create silk some species don't create webs. Next time you find one in your house, don't kill it! Try these UC IPM tips for catching spiders instead.

Finally... maggots.  

A maggot is the emergence of a fly from its egg. Photo from sciencedirect.com.

By the time you see maggots you often have a olfactory experience to reinforce the grossness. Without getting too far into the visual details, we'll focus on the natural history. About half of fly species have larvae known as maggots. Most maggots are important decomposers, feeding on a variety of decaying organic matter. Larvae excrement provide nutrients for molds and other types of fungi and plants. In addition, the bodies of larvae, pupae, and many adult flies are an important food source for animals. 

Even though they may frighten us, as naturalists we can ultimately find an appreciation for these creatures for the important functions they each play in the food web. Use the curiosity of a naturalist and inquiry skills to learn more about them. They may surprise you - and not in a scary way!

References:
Moths info
UC IPM Pestnote 
Jerusalem cricket
Spiders
Natural history of flies