How nature created relationships between different animals – 04/07/2024 – Science

A greenish-brown spongy mass usually forms in large quantities along the surface of the shallow swamps of the Everglades, in southern Florida, in the United States.

At first glance, it may appear to be a proliferation of algae, which sucks oxygen from the water, releasing toxins and suffocating the region’s ecosystem.

But in fact, it is a beautiful and productive gathering of algae and fungi, as well as other unlikely partners, such as plant debris, microbes and bacteria.

This community of beings forms a perfectly adapted relationship known as periphyton. It provides the foundation of the Everglades’ highly biodiverse ecosystem, according to scientist Meenakshi Chabba of the Everglades Foundation, a Florida nonprofit.

For her, “it’s incredible because you have this community of organisms that come together and form this material that is the basis of the entire food chain here.”

Periphyton is an example of mutualism — a relationship between different but unexpectedly close species.

As with any relationship, mutualism involves complex situations of codependency and mutual benefits.

There are two types of mutualism: that which occurs between species that are highly dependent on each other, known as obligatory mutualism; and that between species that have a “friends with benefits” relationship, known as facultative mutualism.

In other words, participants in this last type are able to extract something from the relationship, but would normally survive without the other party.

Periphyton’s slimy mix of algae and fungal matter may not be nature’s most glamorous combination, but it has resulted in a symbiotic romance that has existed “probably hundreds of millions of years,” according to Chabba.

While many of us ponder the ingredients of a good relationship, there are other quite unusual but very successful marriages between the animal and plant kingdoms. These relationships can perhaps offer human beings some loving inspiration.

Woolly bats and carnivorous plants

Not all animals can face the carnivorous plant Nepenthes hemsleyana. But this natural beauty from the island of Borneo, in Southeast Asia, has found its perfect match: the Hardwicke’s woolly bat (Kerivoula hardwickii).

The plant typically suffocates its victims with its sticky drool. But with the bat, it’s different: it attracts it with an echo reflector.

In fact, the plant is not after the bat. The tropical hunter only looks for one thing: the animal’s feces.

Carnivorous plants grow in soil that is low in nutrients. Therefore, they need fertilizer — and feces are perfect food.

In return, the bats find the bed of their dreams. They spend the day resting inside the plant, which offers the animals a safe haven without turning them into food.

Clover roots and sugar-eating bacteria

Legumes (such as beans, peas, chickpeas and clovers) form a symbiotic relationship with bacteria that fix nitrogen from the air in the soil and turn it into ammonia. Plants transform this ammonia into proteins, which they use to grow.

This mutually beneficial relationship has lasted about 60 million years.

In exchange for the help, the plant houses the bacteria in its root nodules —tiny pink spheres— and provides sugars and oxygen so that they can also grow.

So the next time you’re cleaning up the garden and pulling up a clover, look at its roots to marvel at this ancient partnership.

Crocodiles and birds

The curious association between a crocodile and a bird may seem quite unlikely. But the alliance between the Nile crocodile and the crocodile bird was already documented in Antiquity — at least since 440 BC

We know little about what maintains this duo’s partnership. Some experts even argue that the relationship in which the bird cleans the crocodile’s teeth is just a myth.

But there is evidence that crocodiles and wading birds in other parts of the world have a serious relationship.

In the United States, there are wading birds that actively choose their nesting sites above American alligators. The intention is to take advantage of the protection that these reptiles can offer to the nest, warding off other egg-stealing predators.

The benefit to the alligators is the tasty feast provided by the chicks that fall from the nest.

Ostriches and zebras

Ostriches have poor eyesight but a great sense of smell. Zebras can see well, but their sense of smell is terrible. They form a celestial marriage that has been observed since the first records of Charles Darwin (1809-1882).

Zebras and ostriches are often seen together in the African savannas. They help each other by combining their senses to alert each other when predators appear.

And when the partner disappears?

What happens to these mutualisms when one of the species becomes threatened or becomes extinct?

The impact of human beings on the planet, causing loss of habitat or introducing exogenous species that can affect one of the partners, has caused major changes in these relationships and “divorced” many partnerships.

In Hawaii, for example, there are plants that have evolved to fit perfectly into the beaks of the birds that feed on them.

But when these birds go extinct, the plants that depended on them for pollination must go extinct soon after. In other words, the plants have become “widowed” and may not be able to survive without their pollinating partners.

Mutualism can “bring species together toward a common destiny,” as one study on interspecies partnerships noted. The breakdown of the relationship carries with it the potential to expand and accelerate the effects of biodiversity loss and ecosystem disruption.

But it’s not all breakups and separations. Nature is resilient and these species can find ways to survive outside of their symbiotic relationships.

“There are clear cases in which mutualism exhibits a surprising capacity to adapt to global changes — and even cases of the evolution of new partnerships,” says evolutionary biologist Toby Kiers.

Kiers highlights that many of these new partnerships occur with invasive species. This is the case of fungi that develop alliances with non-native eucalyptus trees.

So, for her, “not everything is sadness and desolation.”