Specialist Predators

by Carl Strang

Yesterday I mentioned one hazard that limits the number of katydids that achieve reproductive maturity. Gwynne referred to another danger, this one a group of wasps that specialize on katydids as food for their young. This caught my attention, as two members of genus Sphex have been abundant at Mayslake Forest Preserve in recent years.

The great black wasp is especially common. I have seen as many as 8 at a time visiting swamp milkweed flowers in the south stream corridor prairie.

The great black wasp is especially common. I have seen as many as 8 at a time visiting swamp milkweed flowers in the south stream corridor prairie.

Less abundant, but a consistent presence, great golden diggers likewise catch katydids to feed their young.

Less abundant, but a consistent presence, great golden diggers likewise catch katydids to feed their young.

Each female wasp needs more than one katydid for each egg she lays in her burrow. That can add up to a significant impact on a katydid community. Being aware of such ecological factors enriches our understanding of the local abundance and distribution of singing insects.

A Dietary Hazard

by Carl Strang

Here’s another photo from last summer that was illuminated by information in Darryl T. Gwynne’s book on katydid evolution.

One of the female short-winged meadow katydid nymphs in the sweep net caught and ate a small beetle.

One of the female meadow katydid nymphs in the sweep net caught and ate a small beetle.

Gwynne pointed out that meadow katydids have broad diets that include both plant and animal foods. Carnivory results in a peculiar hazard for these katydids. Many of them pick up horsehair worms, parasites that wait in immature form within other insects, and complete their development within the katydids, killing them in the process. This can significantly reduce the number of katydids that survive to maturity. It seems to me some of the meadow katydids at Mayslake Forest Preserve have diminished abruptly in numbers at times, and this would seem to be one contributing factor.

Spermatophylax

by Carl Strang

For such tiny creatures, insects have complex lives and biology. They have been shaped by natural selection in more ways than we know, but we know enough to be amazed. Recently I began expanding my readings on singing insects, and gained several insights on things I had noticed but hadn’t fully appreciated. Let’s begin with a photo from last summer.

This is the female dusky-faced meadow katydid I caught and photographed last summer at Indiana Dunes National Lakeshore.

This is the female dusky-faced meadow katydid I caught and photographed last summer at Indiana Dunes National Lakeshore.

Note the white gelatinous substance in her jaws. I cropped it out of the photos I shared in the blog then, but fortunately I was not so fastidious as to clean her up. This was a very important meal she was in the midst of consuming, according to Darryl T. Gwynne in his 2001 book, Katydids and Bush-crickets: Reproductive Behavior and Evolution of the Tettigoniidae (Cornell University Press). Another photo tells more of the story.

The female’s abdomen. I was focused on recording the shape of the ovipositor, but notice that more of the white substance is here, as well.

The female’s abdomen. I was focused on recording the shape of the ovipositor, but notice that more of the white substance is here, as well.

It turns out that this female had mated within the previous hour or two, her one and only time (this was surprising, but Gwynne says it is true of all Orchelimum meadow katydids). The male had inserted a spermatophore into her reproductive tract, with this gelatinous structure, called a spermatophylax, as an added extension. The female slowly eats the spermatophylax, which contains valuable nutrients, while fertilization is taking place. This is a significant investment by the male, about 10% of his body mass, and though he may mate again, it will take some time to build a new spermatophore.

Eventually she will eat the protein-rich sperm casing, as well, but by then her eggs will be fertilized. Gwynne studies the evolution of this system, and reviewed it across the worldwide spectrum of katydids in his book. There is some consensus among researchers that the spermatophylax originated as a distraction, preventing the female from immediately consuming the spermatophore and preventing fertilization (she could go on to mate as many times as she wished, building her nutrient reserves at the expense of the males whose sperm did not fertilize her eggs). The question remains, though, as to the degree to which the continued evolution of the spermatophore and its spermatophylax component improves the quality of the offspring by feeding the female. In the Orchelimum meadow katydids it seems that this issue is resolved. The female mates only once, and the male contributes a substantial nutrient gift that increases the size of her eggs. This is why it is really good that I released her without removing the spermatophylax material. It also may be why she was the one I caught, as her focus on her meal probably slowed her down.

Literature Review: Human Paleontology

by Carl Strang

This last post on the scientific literature from 2012 includes notes from studies that spanned the time range of human evolution and geographic expansion. The review begins 4 million years ago with Australopithecus anamensis in Africa, and ends a little over 10,000 years ago in Ohio.

Estebaranz, Ferran, et al. Buccal dental microwear analyses support greater specialization in consumption of hard foodstuffs for Australopithecus anamensis. Journal of Anthropological Sciences, 2012; 90: 1-24 DOI: 10.4436/jass.90006 As described in a ScienceDaily article. Microwear of molars is consistent with a diet of seeds, tubers and leaves for Australopithecus anamensis. This contrasts with the fruit-heavy diets of both the ancestor of anamensis (Ardepithecus ramidus) and its descendant Australopithecus afarensis.

Green, David J., and Zeresenay Alemseged. 2012. Australopithecus afarensis scapular ontogeny, function, and the role of climbing in human evolution. Science 338: 514-517. For the first time, shoulder blades of this species have been studied. Their similarity to those of apes (both in structure and in the fact that those of young are similar to those of adults) suggests that this upright walking species still was adapted for tree climbing as well.

Human use of fire may go back a million years.

Human use of fire may go back a million years.

Berna, Francesco, et al. Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa. Proceedings of the National Academy of Sciences, April 2, 2012 DOI: 10.1073/pnas.1117620109 They found evidence of cultural use of fire dated 1 million years ago, 300,000 years earlier than the previous evidence. This was the time of Homo erectus.

Wilkins, Jayne, Benjamin J. Schoville, Kyle S. Brown, and Michael Chazan. 2012. Evidence for early hafted hunting technology. Science 338:942-946. They found spear points in South Africa from 500,000 years ago, the time of Homo heidelbergensis, the last common ancestor of Neanderthals and modern humans. This indicates that the spears used by both had a common cultural origin. The previous known oldest spears were at 300,000 years ago.

Mathias RA, Fu W, Akey JM, Ainsworth HC, Torgerson DG, et al. (2012) Adaptive Evolution of the FADS Gene Cluster within Africa. PLoS ONE 7(9): e44926. doi:10.1371/journal.pone.0044926 They looked at genes which make possible the conversion of medium-length fatty acids from plants into longer-chain fatty acids essential for human brain function. Variation in human populations and in relation to chimpanzees points to the fixation of these gene variations around 85,000 years ago. This coincides with the time when humans began to expand through Africa away from limited coastal areas, where they had remained for the first 100,000 years of the species’ existence. The authors suggest that prior to this mutational event, humans needed fish and aquatic invertebrates to provide these fatty acids, but afterwards could live in a broader range of environments by including plants in the diet that provided the precursors for the brain chemicals. A ScienceDaily article describing this study points out that African Americans as well as Africans, who have the highest functionality of these genes, more often suffer the side effects of hypertension, coronary artery disease, and other consequences of too-efficient use of vegetable oils in cooking.

Finlayson, C., et al. (2012) Birds of a Feather: Neanderthal Exploitation of Raptors and Corvids. PLoS ONE 7(9): e45927. doi:10.1371/journal.pone.0045927 They studied remains in a number of caves and other Neanderthal sites over a long span of time, and found evidence that Neanderthals commonly and deliberately, removed corvid and raptor flight feathers, apparently for use in symbolic adornment.

Rule, Susan, et al. 2012. The aftermath of megafaunal extinction: ecosystem transformation in Pleistocene Australia. Science 335:1483-1486. They used charcoal as an indicator of human activity, a fungal dung spore for megafauna, and also looked at changes in plant communities as indicated by pollen in core samples over a time span from 130,000 to 24,000 years ago. They conclude that human hunting was responsible for Australian megafauna extinctions (at least 20 genera of marsupials, monotremes, birds and reptiles). They then argue that the timing of vegetation changes points to the loss of megafauna leading to an increase in grasses and other fine fuels, so that resulting wildfires promoted a vegetation change in the region around the cored swamp in northeast Australia, from a mixed rainforest to a desert shrub-grass ecosystem.

Human use of fire may go back a million years.

Reconstructed ground sloth

Brian G. Redmond, H Gregory McDonald, Haskel J. Greenfield, Matthew L. Burr. New evidence for Late Pleistocene human exploitation of Jefferson’s Ground Sloth (Megalonyx jeffersonii) from northern Ohio, USA. World Archaeology, 2012; 44 (1): 75 DOI: 10.1080/00438243.2012.647576 A fossil thigh bone shows saw marks from stone tools were used to filet the muscle, 13,435-13,738 years ago.

Lessons from Travels: Glaucous Gull Hybrids

by Carl Strang

I conclude the Lessons from Travels series with a question that remains open to this day. Why does a portion of the glaucous gull population at the tip of the Yukon-Kuskokwim Delta show signs of hybridization with another species?

Glaucous gulls in a nesting colony

Glaucous gulls in a nesting colony

My study required me to shoot a limited number of gulls for various measurements both external and internal, and I found that the wingtips of some of them showed faint gray patterns reminiscent of other species. The eyes also occasionally showed darker color variations different from the pale glaucous gull ideal. This is what took me to Adak Island.

The nearest candidates for hybridization were glaucous-winged gulls, which are common in the Aleutians.

The nearest candidates for hybridization were glaucous-winged gulls, which are common in the Aleutians.

I documented the descriptive data (DNA comparisons were well in the future), but could not reach a clear conclusion. Two decades later I was contacted by Tim Bowman, a wildlife biologist with the U.S. Fish and Wildlife Service in Alaska, who was doing impressive work with glaucous gulls in the same region. He had found that the gull population had ballooned, thanks to improved gull winter survival off the Alaska fishing industry. He also looked at the hybridization question I had raised. By then, molecular studies were feasible but very expensive, and he had not found the funds to proceed. He did note, however, that there did not appear to be a graded change in those physical measures connecting the glaucous and glaucous-winged gull populations. Perhaps someday someone will clarify this, but all in all it has to be regarded as more a curiosity than an important question.

Still Winter at Mayslake

by Carl Strang

The calendar claims that spring has arrived, but it’s still winter at Mayslake. A while back I mentioned my 6 seasons framework for northeast Illinois. The first of March brings the start of our sixth season, Late Winter. I once held too rigidly to the idea that Late Winter ends in mid-April, but especially after last year I feel the need to modify the framework and acknowledge that this season is variable in length. I have an idea of how to mark the end of Late Winter, which I will share later. For now, it is shaping up to be a relatively late spring. Consider the lake ice at Mayslake Forest Preserve. This year the ice was thick enough to support people, though few took advantage of the opportunity.

Forest Preserve District rangers placed these fish structures out on the Mays’ Lake ice early in March.

Forest Preserve District rangers placed these fish structures out on the Mays’ Lake ice early in March.

In my previous 4 springs at Mayslake, the latest there was ice on the lakes was March 18. This year it has been slow to depart.

Mays’ Lake was almost entirely ice covered on March 13.

Mays’ Lake was almost entirely ice covered on March 13.

By March 19 the fish structures had sunk, but the lake still was largely in ice. The previous late date for lake ice in my 5 years at Mayslake was March 18. The ice still was there through yesterday (the 21st).

By March 19 the fish structures had sunk, but the lake still was largely in ice. The previous late date for lake ice in my 5 years at Mayslake was March 18. The ice still was there through yesterday (the 21st).

Meanwhile the stream corridor marsh, though open and frozen in turns, has filled to capacity and beyond.

The marsh on March 6.

The marsh on March 6.

Snows have allowed the continued opportunity for tracking.

A mink has been passing through the preserve on a weekly basis.

A mink has been passing through the preserve on a weekly basis.

A pair of coyotes has been a more regular presence on the preserve as well, as have red-tailed hawks. I am thinking I should soon conduct a search for a new den and a new nest, respectively. It has become clear, though, that if the great horned owls are nesting this year, they are off the preserve to the south.

Ruby-throated Hummingbird Dossier

by Carl Strang

This week’s species dossier covers my observations of our only eastern hummingbird, the ruby-throated.

Hummingbird, Ruby-throated

Young or female ruby-throated hummingbird

Young or female ruby-throated hummingbird

1986. To this point I have seen hummingbirds in the Culver, Indiana, area, near Jeffersonville, Indiana, in south central Pennsylvania, once in fall migration at Ann Arbor, Michigan, in Maryland on the Delmarva Peninsula, and in Virginia. They visit flowers, especially bright orange or red ones including trumpet creeper, cardinal flower, and jewelweed. They are occasional migrants at Willowbrook Wildlife Center, DuPage County, Illinois. They seem to require forests or woods edges.

15SE87. Young or female hummer (dark stripes on pale throat) feeding from orange jewelweed, midday, Willowbrook.

27JL99. Hummingbird made brief appearance near Willowbrook picnic shelter.

22AU99. Hummer on jewelweed at West DuPage Woods Forest Preserve.

8&17SE99. Migrant hummers at Willowbrook.

Hummingbird at wild bergamot, my back yard.

Hummingbird at wild bergamot, my back yard.

8MY00. Arboretum. At parking lot 23, a hummingbird nest, perhaps still under construction because it is pale and obvious, well out from the trunk of a tamarack on a horizontal branch 20 feet up.

15JE00. Arboretum. At Parking Lot 23, hummingbird female is on the nest, which does not stand out as much as last week (outer surface has more material added).

17JE00. Arboretum. The hummingbird female leaves the nest frequently, perhaps for 30 seconds every 5 minutes.

16JE01. Arboretum, Heritage Trail. Many scattered fire pinks are flowering, and a hummer was visiting one of them briefly, then moved on.

22AU(year not indicated). West DuPage Woods. A hummingbird on jewelweed.

2AU04. An immature or female hummingbird visited the royal catchflies in my back yard flowerbeds.

21JL06. An immature or female hummingbird at back yard royal catchflies.

15JL09. First immature or female hummer visiting the first royal catchflies, also bergamot and the last white wild indigo flowers.

Hummingbird at cardinal flower, Mayslake

Hummingbird at cardinal flower, Mayslake

24AU10. Mayslake. A hummingbird visiting cardinal flowers and Liatris near the bridge.

Literature Review: The Cenozoic Era

by Carl Strang

This week we look at some recent studies of the time between the Mesozoic Era and the present day. In recent years there has been much interest in the dynamics of climate change across the ages of the Earth.

A huge amount of carbon today is sequestered in the permafrost soils of the North.

A huge amount of carbon today is sequestered in the permafrost soils of the North.

Robert M. DeConto, et al. Past extreme warming events linked to massive carbon release from thawing permafrost. Nature, 2012; 484 (7392): 87 DOI: 10.1038/nature10929 They combined modeling with the Earth’s orbital dynamics to show the likelihood that in the Paleocene, when the Earth’s orbit became more eccentric and tilt became greater, this resulted in thawing and decomposition of permafrost, releasing huge amounts of carbon dioxide and resulting in a positive feedback loop that produced the Paleocene-Eocene Thermal Maximum.

Pitcher plants, Big Thicket. The following study traces their origin.

Pitcher plants, Big Thicket. The following study traces their origin.

Ellison AM, et al. (2012) Phylogeny and Biogeography of the Carnivorous Plant Family Sarraceniaceae. PLoS ONE 7(6): e39291. doi:10.1371/journal.pone.0039291 They studied nuclear, mitochondrial and plasmid genes to sort out relationships and evolutionary history of the pitcher plants. They conclude that the family appeared in South America 44-53mya (million years ago, Eocene), and by the end of the Eocene was widespread in North and South America.

G. Grellet-Tinner, et al. (2012) The First Occurrence in the Fossil Record of an Aquatic Avian Twig-Nest with Phoenicopteriformes Eggs: Evolutionary Implications. PLoS ONE 7(10): e46972. doi:10.1371/journal.pone.0046972 They found fossils of a basal flamingo in association with eggshells and a floating nest that are like those of modern grebes, in an early Miocene shallow-lake wetland with high evaporation, in Spain. Though they agree that there was an earlier split between the grebes and the flamingos, they mention that fossil flamingos are known from the Oligocene, grebes from the Miocene. Apparently the bones are insufficient to provide much of an understanding of this early flamingo’s appearance.

Zhang Z, Feduccia A, James HF (2012) A Late Miocene Accipitrid (Aves: Accipitriformes) from Nebraska and Its Implications for the Divergence of Old World Vultures. PLoS ONE 7(11): e48842. doi:10.1371/journal.pone.0048842 They describe a fossil bird from Nebraska that links New World hawks and eagles to the Gypaetinae, one of the subfamilies of Old World vultures. This places the timing of that group’s origin in the Miocene, and supports its evolutionary separation from the other Old World vulture subfamily, the Aegypiinae.

Elderfield, H., et al. 2012. Evolution of ocean temperature and ice volume through the mid-Pleistocene climate transition. Science 337:704-709. (Comment by Peter U. Clark on pp. 656-658 in the same issue). They sorted through various isotopic proxies in marine sediments from New Zealand, and found an association between the mysterious change in ice age periodicity around 900,000 years ago (from cycles of 41,000 years to the more recent cycles of 100,000 years, a change not connected to the Earth orbit fluctuations now known to be the underlying cause of ice age cycling generally) and an increase in the volume of ice around Antarctica. They suggest that “an anomalously low Southern Hemisphere summer insolation” failed to melt the Antarctic ice during one interglacial period, and that the ice added during the following ice age was enough to produce the observed period change. The sea level drop during ice ages changed from 70 meters to 120 meters as a result. Their data also argue against a gradual cooling, from changes in atmospheric carbon dioxide, as the primary driver of the periodicity change.

Jeremy D. Shakun, et al. Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature, 2012; 484 (7392): 49 DOI: 10.1038/nature10915 From an article in ScienceDaily: “Here is what the researchers think happened.

“Small changes in Earth’s orbit around the sun affected the amount of sunlight striking the northern hemisphere, melting ice sheets that covered Canada and Europe. That fresh water flowed off of the continent into the Atlantic Ocean, where it formed a lid over the sinking end of the Atlantic Meridional Overturning Circulation — a part of a global network of currents that brings warm water up from the tropics and today keeps Europe temperate despite its high latitudes.

“The ocean circulation warms the northern hemisphere at the expense of the south, the researchers say, but when the fresh water draining off the continent at the end of the last Ice Age entered the North Atlantic, it essentially put the brakes on the current and disrupted the delivery of heat to the northern latitudes.

“ʻWhen the heat transport stops, it cools the north and heat builds up in the Southern Hemisphere,ʼ Shakun said. ʻThe Antarctic would have warmed rapidly, much faster than the time it takes to get CO2 out of the deep sea, where it was likely stored.

“ʻThe warming of the Southern Ocean may have shifted the winds as well as melted sea ice, and eventually drawn the CO2 out of the deep water, and released it into the atmosphere,ʼ Shakun said. ʻThat, in turn, would have amplified warming on a global scale.ʼ”

The study was a global review of the timing of temperature and atmospheric carbon dioxide changes at the end of the last period of continental glaciation.

Lessons from Travels: Down Under

by Carl Strang

As I wind down the Lessons from Travels series, I find a few topics remain to be mentioned from my trip to Australia. First, here’s a warning to those planning to drive in countries where cars go in the left lane. It’s not enough to visualize driving in the left lane. Remember that you will be sitting on the right side of the car. I pulled out of the car rental facility near the ferry depot in Tasmania, and immediately went up on the sidewalk at the left edge of the roadway. Fortunately no one else was around, and I quickly adjusted to my position in the lane, as well as the car’s.

The next point is that road kill looks strange. That’s because the fauna are strange. After all, the Australian mammals are mainly marsupials, and they will look different in flattened form from our North American car carrion.

We have nothing that looks like a pademelon.

We have nothing that looks like a pademelon.

Though both are marsupials, their possums are different from our opossums.

Though both are marsupials, and produce similar footprints, their possums are different from our opossums.

Finally, there is the matter of celestial bodies. The sky is inverted from our North American perspective. The sun appears to move counterclockwise above the northern horizon. At night, the moon is upside down. Orion stands on his head. Finally, you get to see the southern constellations and stars. There are fewer bright stars, and the sky consequently is less filled by bright, distinctive constellations. But then, there’s the Southern Cross, which makes up for a lot.

Common Mullein in Winter

by Carl Strang

Biennial plants often have two winter forms. Their first year ends with a ground-hugging, basal rosette or cluster of leaves that often remains green through the cold months. The second year they flower, produce seeds, and die, leaving the spent stalk for the second winter. Today’s example is the common mullein.

Here is a winter rosette as it appears in March.

Here is a winter rosette as it appears in March.

The leaves are thick and velvety fuzzy. The second-year stalks are what I call cognates, as they are not all that different in appearance from their growing season form.

The leaves have collapsed, and the plant has turned brown, but the plant’s stature, thick stem and fruiting tip are unique.

The leaves have collapsed, and the plant has turned brown, but the plant’s stature, thick stem and fruiting tip are unique.

The densely clustered capsules at the tip of the stem.

The densely clustered capsules at the tip of the stem.

And here is one such tip in bloom.

And here is one such tip in bloom.

Mullein is not native, but as far as I know it is not particularly invasive.

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