Wildlife in Indian cities and national parks


This May 2020 video says about itself:

Urban wildlife lives in cities with people – Black kites, rats, wild boars, ravens, crows, snakes. Wildlife in nature lives in national parks and reserves – tigers, dholes, elephants, gaurs, deer, mongooses, monkeys, snakes.

We want to show that we need to value biodiversity and realize that most species live in natural habitats. On the other side, it is amazing to watch how well some animals survive in the cities.

Black kites (Milvus migrans) are birds of prey living in Europe, Africa, Asia, and Australia. They are very good at surviving close to people. In many places they scavenge.

Baby leatherback turtles, video


This 5 May 2020 video says about itself:

Baby Turtles Hatch And Race To The Ocean | VR 360 | Seven Worlds, One Planet

Leatherback sea turtle hatchlings are just emerging from the sand on a desert island beach in the Caribbean. Stay in and explore as they make their way to the sea for the very first time.

Ancient Devonian fossil plant, new discovery


Barinophyton spp.

From Stanford’s School of Earth, Energy & Environmental Sciences in the USA:

New ancient plant captures snapshot of evolution

May 4, 2020

Summary: Researchers have discovered an ancient plant species whose reproductive biology captures the evolution from one to two spore sizes — an essential transition to the success of the seed and flowering plants we depend on

In a brilliant dance, a cornucopia of flowers, pinecones and acorns connected by wind, rain, insects and animals ensure the reproductive future of seed plants. But before plants achieved these elaborate specializations for sex, they went through millions of years of evolution. Now, researchers have captured a glimpse of that evolutionary process with the discovery of a new ancient plant species.

The fossilized specimen likely belongs to the herbaceous barinophytes, an unusual extinct group of plants that may be related to clubmosses, and is one of the most comprehensive examples of a seemingly intermediate stage of plant reproductive biology. The new species, which is about 400 million years old and from the Early Devonian period, produced a spectrum of spore sizes — a precursor to the specialized strategies of land plants that span the world’s habitats. The research was published in Current Biology May 4.

“Usually when we see heterosporous plants appear in the fossil record, they just sort of pop into existence,” said the study’s senior author, Andrew Leslie, an assistant professor of geological sciences at Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “We think this may be kind of a snapshot of this very rarely witnessed transition period in evolutionary history where you see high variation amongst spores in the reproductive structure.”

A major shift

One of the most important time periods for the evolution of land plants, the Devonian witnessed diversification from small mosses to towering complex forests. The development of different spore sizes, or heterospory, represents a major modification to control reproduction — a feature that later evolved into small and large versions of these reproductive units.

“Think of all the different types of sexual systems that are in flowers — all of that is predicated on having separate small spores, or pollen, and big spores, which are inside the seeds,” Leslie said. “With two discrete size classes, it’s a more efficient way of packaging resources because the big spores can’t move as easily as the little ones, but can better nourish offspring.”

The earliest plants, from between 475 million to 400 million years ago, lacked reproductive specialization in the sense that they made the same types of spores, which would then grow into little plantlets that actually transferred reproductive cells. By partitioning reproductive resources, plants assumed more control over reproduction, according to the researchers.

The new species, together with the previously described plant group Chaleuria of the same age, represents the first evidence of more advanced reproductive biology in land plants. The next example doesn’t appear in the fossil record until about 20 million years later.

“These kinds of fossils help us locate when and how exactly plants achieved that kind of partitioning of their reproductive resources,” Leslie said. “The very end of that evolutionary history of specialization is something like a flower.”

A fortuitous find

The researchers began analyses of the fossils after they had been stored in the collections at the Smithsonian National Museum of Natural History for decades. From about 30 small chips of rock originally excavated from the Campbellton Formation of New Brunswick in Canada by late paleobotanist and study co-author Francis Hueber, they identified more than 80 reproductive structures, or sporangia. The spores themselves range from about 70 to 200 microns in diameter — about a strand to two strands of hair. While some of the structures contained exclusively large or small spores, others held only intermediate-sized spores and others held the entire range of spore sizes — possibly with some producing sperm and others eggs.

“It’s rare to get this many sporangia with well-preserved spores that you can measure,” Leslie said. “We just kind of got lucky in how they were preserved.”

Fossil and modern heterosporous plants primarily live in wetland environments, such as floodplains and swamps, where fertilization of large spores is most effective. The ancient species, which will be formally described in a follow-up paper, has a medley of spores that is not like anything living today, Leslie said.

“The overarching story in land plant reproduction is one of increased division of labor and specialization and complexity, but that has to begin somewhere — and it began with simply producing small spores and big spores,” Leslie said. “With these kinds of fossils, we can identify some ways the plants were able to do that.”

Co-authors of the study are from Brown University, the University of North Carolina — Chapel Hill and the University of Sheffield.

How salmon find the way back home


This video from New Zealand says about itself:

Chinook Salmon Spawning April 2019

This series of videos captures a pair of sea run chinook salmon spawning twice in the same Redd in a Canterbury stream bed. The spawning acts in the video are at 5:15 and 13:45.

From Oregon State University in the USA:

Magnetic pulses alter salmon’s orientation, suggesting navigation via magnetite in tissue

May 4, 2020

Researchers in Oregon State University’s College of Agricultural Sciences have taken a step closer to solving one of nature’s most remarkable mysteries: How do salmon, when it’s time to spawn, find their way back from distant ocean locations to the stream where they hatched?

A new study into the life cycle of salmon, involving magnetic pulses, reinforces one hypothesis: The fish use microscopic crystals of magnetite in their tissue as both a map and compass and navigate via the Earth’s magnetic field.

Findings were published in the Journal of Experimental Biology.

Researchers including David Noakes, professor of fisheries and wildlife at OSU and the director of the Oregon Hatchery Research Center, subjected juvenile chinook salmon to a type of brief but strong magnetic pulse known to reverse the polarity of magnetic particles and affect magnetic orientation behavior in other animals.

Orientation behavior of pulsed salmon and un-pulsed control fish were compared in a magnetic coil system under a pair of conditions: the local magnetic field, and one in which “map-like” information from the magnetic field had been shifted.

In the local field, pulsed and un-pulsed fish oriented almost identically. But after the magnetic map was shifted, the test and control salmon behaved much differently from each other — the control fish were randomly oriented and the pulsed fish displayed a preferred heading.

The difference in behavior suggests that chains of magnetite, which would have been altered by the pulse, may play a role in the navigation system of salmon.

Magnetic pulses are known to alter magnetic orientation behavior in a range of terrestrial and aquatic animals, among them mole rats, bats, birds, sea turtles and lobsters. The study by Noakes and colleagues at Oregon State, the University of North Carolina and LGL Ecological Research Associates, Inc. is the first evidence linking a magnetic pulse to behavioral changes in fish.

Magnetite, an oxide of iron and one of the primary iron ores, is expressed chemically as Fe3O4 and is the most magnetic of the Earth’s naturally occurring minerals. Naturally magnetized magnetite is known as lodestone and was ancient people’s introduction to the concept of magnetism.

Magnetite is the basis for one of two ways salmon are thought to find their way around; the other is the theory of chemical magnetoreception, which suggests biochemical reactions influenced by the ambient magnetic field are a navigational tool.

“In the big picture, these salmon know where they are, where they’re supposed to be, how to get there and how to make corrections if needed,” said Noakes, the study’s corresponding author. “While they’re in freshwater, they’re imprinting upon the chemical nature of the water. When they hit saltwater, they switch over to geomagnetic cues and lock in that latitude and longitude, knowing they need to come back to those coordinates. And when they decide to come back, it’s months in advance because they’re halfway to Japan.”

After reaching the mouth of the river that took them to the ocean, the salmon swim upstream to spawn at the exact location where they hatched.

“In the river they seem to rely upon chemical signals,” Noakes said. “There’s ongoing research looking into that.”

The magnetic pulse could have affected the salmon’s map, compass or both, Noakes said.

“Our findings are consistent with the hypothesis that magnetoreceptors are based on magnetite crystals,” he said. “But we’ll need more research to confirm or refute this hypothesis and to definitively characterize the mechanisms that underlie magnetoreception in fish. We’re trying to figure out the life cycle of the salmon from the points of highest information — when they go from freshwater to saltwater and when they turn around and come back.”