Random photos from the field; taken last week just south of Tampa, Florida.
Possibly Isomira pulla ???
Great Egret; Casmerodius albus
Random photos from the field; taken last week just south of Tampa, Florida.
Possibly Isomira pulla ???
Great Egret; Casmerodius albus
Despite its common name ‘sea lavender’ is a member of the Plumbaginaceae Family, which means that it isn’t really a ‘lavender’ at all, as lavenders belong to the Lamiaceae Family. One of the plant’s unique characteristics is that it’s one of only a handful of the Limonium genera’s 120 species with a range limited to North America; the majority of the genera’s members show a much more global distribution. Here in Florida, the Obligate can be found near saltwater or brackish marshes, or as with the one in the above photo, in mangrove swamps.
Limonium carolinianum is an herbaceous perennial with a woody rhizome and alternating leaves. The leaves themselves are basal, generally elliptic in shape and have a leathery feel when touched. The flowers display five stamens, and a five-lobed, whitish colored calyx with a corolla that ranges from blue to lavender. The fruits of the sea lavender bear a single maroon colored seed, which as with the plant’s range mentioned above, represent another unique characteristic. More specifically, the seeds’ morphology and structure have undergone adaptation as to tell-the-tale of plant’s favored mode of geographic conquest.
The brownish-red seeds of the sea lavender are relatively large and display a sheen that likely attracts birds. The plant’s habitat preference for saltwater proximal real-estate when combined with the sheen displayed by its seeds may work cohesively to facilitate dispersal of its genome. As Charles Darwin pointed out on page 361 of the Origin of Species,
“Living birds can hardly fail to be highly effective agents in the transportation of seeds.”
This is likely true of Limonium carolinianum, a plant species that has adapted to near-sea environments that are frequented by shore birds.
Characters from the ‘Ice Age 2’ ; glacier and glacial lake (Lake Agassiz?) in background.
During the Wisconsin glaciations about 12,000 years before the present, a massive continental ice sheet covered most of what is today the United States and Canada. As the Wisconsin came to a close, rising temperatures instigated its receding glaciers to form a colossal lake; roughly centered on modern day Manitoba. The lake was uniquely positioned in such a way that a combination of topography and its inclusive glacial blockades trapped the discharge of meltwater. The glacial melt, being unable to drain, resultantly accumulated in a water body that covered nearly half of a million square kilometers – Lake Agassiz. As in the animated movie, once sufficient hydrology was achieved to overcome its restricting geography and ice, the water was released in a catastrophic flooding event of incomprehensible immensity. However, unlike the cartoon’s scripted drama, the direst impact to fauna 12,000 years ago wasn’t the risk of drowning; the biggest consequence of the flood was its affects to global climate.
The enormous quantity of water released from the rupture of Lake Agassiz’s glacial banks, as opposed to flowing directly southward, chose to exit by way of the Saint Lawrence River. Following the St. Lawrence, the freshwaters moved eastward and into the North Atlantic. Once in the North Atlantic, the vast icy water cooled the warmer North Atlantic Current, and rapidly diluted the saline gradients that help drive its heat-conveying waters. Known as thermohaline circulation, variations in ocean water density create flow patterns that convey heat from regions proximal to the equator to those areas located more pole-ward; the constituent variations in density are brought about by surficial heat and saline content. The rupture of Lake Agassiz impacted the thermohaline circulation of the North Atlantic Current, altered heat transfer to the northern hemisphere, and drastically changed the Pleistocene climate of the North American Continent. The rapid climate change associated with the Lake Agassiz event is known as the Younger Dryas stadial (a ‘stadial’ is the name assigned to a period of cooling temperatures).
During the Younger Dryas stadial, mean annual temperatures throughout large portions of the Northern Hemisphere plummeted by as much as five-degrees Celsius. The drop in temperature caused some regions to re-glaciate, despite what had until recently been a warming trend. Climate change forced ecosystems into flux, and likely contributed to the extinction of several genera of mammals – The End Pleistocene Extinction Event.
The End Pleistocene Extinction Event marked the end of the road for some of the characters portrayed in the Ice Age movie, saber-toothed cats, giant sloths, mastodons and similar mammals. As a matter of fact, a recent article in Science collaborated the extinction chronology for more than 30 genera of Pleistocene fauna; the study used data from FAUNMAP to determine that the extinctions occurred nearly simultaneously.
Although much is known about the Younger Dryas stadial, its exact contribution to the End Pleistocene Extinction is still largely a matter for debate. Complicating the issue is the immigration of Clovis people into North America at about the same time that the Younger Dryas was putting a strangle-hold on the climate. The Clovis may have participated in the mammals’ disappearance through hunting – the Overkill Hypothesis.
Faith, J., & Surovell, T. (2009). Synchronous extinction of North America's Pleistocene mammals Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0908153106
The abundance of Hypericum fasciculatum, when combined with its multi-branched physiognomy and its habitat preference for plentiful water, make the plant an integral component of aquatic ecosystems here in Florida. As mentioned previously, the structure provided by the plant’s branches, branchlets and leaves attract a myriad of arthropod species. Once attracted by the ‘peelbark,’ these same arthropods will, in turn, move to occupy niches in proximity to the plant. There they’ll take on roles as pollinators, predators and prey for other organisms. Through such species interactions, the trophic effects of seemingly unconnected organisms become intertwined and bound.
As an example of how complex life histories can become tangled, consider for a moment a hypothetical swamp in which a hypothetical fish is swimming around the exfoliated base of a hypothetical Hypericum fasciculatum …
As with many fish, the hypothetical one feeds on aquatic insects like water beetles, mayflies and larval dragonflies. Examining dragonflies in particular, the loss of dragonfly larvae via fish predation ultimately results in the emergence of fewer adult dragonflies than would be predicted in the absence of the fish. Compounding the process further, the presence of fewer adult dragonflies in nearby ecological communities translates to less aerial predation of flying insects. Flying insects, in addition to being food-stuffs for dragonflies, also pollinate plants; from this relationship it can be inferred that with fewer dragonflies, more insect pollinators find the nectar-rich flowers they seek… The end result of this hypothetical situation is that the Hypericum’s proximity to the fish allows the plant to host a greater number of pollinators, and thus to experience a greater level of reproductive success itself.
Image from Cited Article, interaction web showing the pathway by which fish facilitate plant reproduction. Solid arrows ndicate direct interactions; dashed arrows denote indirect interactions. The sign refers to the expected direction of the direct or indirect effect.
As is characteristic of most ecosystem dynamics, the above scenario can also be run in reverse to show that the presence of the common Hypericum fasciculatum could lead to increased fitness in the hypothetical fish species.
Knight, T., McCoy, M., Chase, J., McCoy, K., & Holt, R. (2005). Trophic cascades across ecosystems Nature, 437 (7060), 880-883 DOI: 10.1038/nature03962
The green lynx spider is a member of the Oxyopidae Family and accordingly displays several traits characteristic for the group. In terms of identifying morphology, members of the group show a hexagon-like pattern of eye arrangement, and legs that bear large spines. Behaviorally, members of the Oxyopidae are aggressive daytime hunters which, as opposed to constructing webs, stalk their prey over the leaves and stems of the herbaceous groundcover. In regards to Peucetia viridans specifically, the spider’s body is translucent and exhibits a bright green coloration with red spots on the cephalothorax and black spots on its spiny legs.
Considering the presence of an egg sac and the sentinel-like bearing demonstrated by the spider appended to the sunflower, it was very likely a female. As a strategy, females of the species uncompromisingly guard their reproductive investment using a variety of tactics. These protective measures are necessitated by the low-to-the-ground habitat they share with a number of other voracious predators. Here in Florida, some of the most abundant and hostile species encountered by lynx spiders are fire ants (Solenopsis spp.)
The specific tactic used to defend an egg sac from fire ant onslaught is dependent on the intensity of the ant attack. Intensity is here a measure of ant quantity and the frequency of assault. Generally, female lynx spiders will utilize a mode of defensive escalation in which infrequent or isolated attacks from a single ant will be dealt with through deployment of a rapid and violent head-on confrontation. As the ant approaches the female, she’ll pounce forward and use her mass to knock the assailant from the plant, or, if failing to physically remove the ant, she’ll alternatively utilize her fangs to pierce the exoskeleton of her antagonist, ultimately slaying the provoker. The spider will almost always prevail during one-on-one combat with an ant, however if the ant attack is undertaken in number, evasion becomes the best option for the lynx.
If the incidences of attack become too frequent, or if the ants attack in larger quantities, mother Peucetia viridans will attempt to dissuade the egg-seeking aggressors by removing the prize for which they hunger – she’ll move the eggs out of reach. Once again depending on the seriousness and intensity of the ants’ offensive maneuvers, she’ll execute one of two evasive actions. One option is to cut all but a couple of the silk cables holding the egg sac in place, causing it drop from its anchor point and remain suspended in air; the second option to completely untie the sac and relocate to an entirely new host plant. The suspension method removes the eggs from hostility and forces any persistent attackers to travel down individual threads to continue pursuit – where they’ll undoubtedly meet an agitated mother face-to-face. Relocating the egg sac to a new host is a sure-fire way to end the current dispute however it is a risky option, because increased visibility during transport may leave both the mother and her eggs vulnerable to other hungry predators.
Eubanks, M. (2001). Estimates of the Direct and Indirect Effects of Red Imported Fire Ants on Biological Control in Field Crops Biological Control, 21 (1), 35-43 DOI: 10.1006/bcon.2001.0923
Linda S. Fink (1987). Green Lynx Spider Egg Sacs: Sources of Mortality and the Function of Female Guarding (Araneae, Oxyopidae Journal of Arachnology, 15 (2), 231-239
Climbing aster, unlike the majority of the other varieties in the genus (which are herbaceous), presents as a many branched shrub with a woody stem base and often even woody branches. The Obligate plant displays numerous leaves that range from elliptic to lanceolate in shape. The flowers are typically about an inch in diameter and generally have a light-blue or light-purple color.
Aster carolinianus is native to the coastal plain of the southeastern United States and is often found residing in marshes, along stream banks and - as pictured above - in freshwater swamps.
As a characteristic trait, the climbing aster has the habit of entangling itself in the branches of surrounding plants, or even tying itself in large tousled masses.
Asterales, the order to which the Asteraceae family belongs, has origins in the Cretaceous period about 100 million years ago and probably experienced diversification during the Oligocene and Miocene. In regards to their evolutionary past, recent research by Tom Viaene (et al) examined the variability of stamen and petal morphologies within the basal asterid families. Through comparisons of the genes that coded for these floral structures, he determined that the early members of the asterid group likely duplicated the petal and stamen genes as a strategy for moving into a wider range of niches.
The above images were taken last week near St. Marks National Wildlife Refuge in northern Florida.
Viaene, T., Vekemans, D., Irish, V., Geeraerts, A., Huysmans, S., Janssens, S., Smets, E., & Geuten, K. (2009). Pistillata--Duplications as a Mode for Floral Diversification in (Basal) Asterids Molecular Biology and Evolution, 26 (11), 2627-2645 DOI: 10.1093/molbev/msp181