Origin and Early Evolution of Hydrocharitaceae and the Ancestral Role of Stratiotes

Funding Information: This study was funded by the Austrian Science Fund (FWF) with a grant to F.G., project number P34303; Open Access Funding by the University of Vienna. For the purpose of open access, the author has applied a CC BY public copyright license to any author accepted manuscript version arising from this submission. Publisher Copyright: © 2024 by the authors.The combined morphological features of Stratiotes (Hydrocharitaceae) pollen, observed with light and electron microscopy, make it unique among all angiosperm pollen types and easy to identify. Unfortunately, the plant is (and most likely was) insect-pollinated and produces relatively few pollen grains per flower, contributing to its apparent absence in the paleopalynological record. Here, we present fossil Stratiotes pollen from the Eocene of Germany (Europe) and Kenya (Africa), representing the first reliable pre-Pleistocene pollen records of this genus worldwide and the only fossils of this family discovered so far in Africa. The fossil Stratiotes pollen grains are described and compared to pollen from a single modern species, Stratiotes aloides L. The paleophytogeographic significance and paleoecological aspects of these findings are discussed in relation to the Hydrocharitaceae fossil records and molecular phylogeny, as well as the present-day distribution patterns of its modern genera.publishersversionpublishe

Origin and Early Evolution of Hydrocharitaceae and the Ancestral Role of Stratiotes

The combined morphological features of Stratiotes (Hydrocharitaceae) pollen, observed with light and electron microscopy, make it unique among all angiosperm pollen types and easy to identify. Unfortunately, the plant is (and most likely was) insect-pollinated and produces relatively few pollen grains per flower, contributing to its apparent absence in the paleopalynological record. Here, we present fossil Stratiotes pollen from the Eocene of Germany (Europe) and Kenya (Africa), representing the first reliable pre-Pleistocene pollen records of this genus worldwide and the only fossils of this family discovered so far in Africa. The fossil Stratiotes pollen grains are described and compared to pollen from a single modern species, Stratiotes aloides L. The paleophytogeographic significance and paleoecological aspects of these findings are discussed in relation to the Hydrocharitaceae fossil records and molecular phylogeny, as well as the present-day distribution patterns of its modern genera

Insect herbivory within modern forests is greater than fossil localities

Fossilized leaves provide the longest running record of hyperdiverse plant-insect herbivore associations. Reconstructions of these relationships over deep time indicate strong links between environmental conditions, herbivore diversity, and feeding damage on leaves. However, herbivory has not been compared between the past and the modern era, which is characterized by intense anthropogenic environmental change. Here, we present estimates for damage frequencies and diversities on fossil leaves from the Late Cretaceous (66.8 Ma) through the Pleistocene (2.06 Ma) and compare these estimates with Recent (post-1955) leaves collected via paleobotanical methods from modern ecosystems: Harvard Forest, United States; the Smithsonian Environmental Research Center, United States; and La Selva, Costa Rica. Total damage frequency, measured as the percentage of leaves with any herbivore damage, within modern ecosystems is greater than any fossil locality within this record. This pattern is driven by increased frequencies across nearly all functional feeding groups within the Recent. Diversities of total, specialized, and mining damage types are elevated within the Recent compared with fossil floras. Our results demonstrate that plants in the modern era are experiencing unprecedented levels of insect damage, despite widespread insect declines. Human influence, such as the rate of global climate warming, influencing insect feeding and timing of life cycle processes along with urbanization and the introduction of invasive plant and insect species may drive elevated herbivory. This research suggests that the strength of human influence on plant-insect interactions is not controlled by climate change alone but rather, the way in which humans interact with terrestrial landscape

Appendix B. Woody dicot species and morphotypes in the Bighorn Basin floras.

Woody dicot species and morphotypes in the Bighorn Basin floras

Supplement 1. Complete insect damage data set from the nine Paleocene–Eocene Bighorn Basin sites described in this paper.

<h2>File List</h2><blockquote> <p><a href="data.txt">data.txt</a></p> </blockquote><h2>Description</h2><blockquote> <blockquote> <p>The complete insect damage data set shown as a list of every identifiable dicot leaf, its size, and the damage types on it.</p> <p>Column definitions:</p> <blockquote> <p>Site: Bighorn fossil plant sites. P = Paleocene, E = Eocene. Site numbers within the Paleocene and Eocene are chronologic, from oldest to youngest.</p> <p>USNM Locality Number: Formal locality number assigned by the National Museum of Natural History, Smithsonian Institution. Sites E2, E3, and E5 consist of multiple localities at the same (or very nearly the same) stratigraphic level, and so each locality was given its own USNM locality number.</p> <p>Collector's Locality Number: Informal, preliminary locality number assigned in the field. EDC = Ellen Currano, SW = Scott Wing, PW = Peter Wilf. LB and DC1 were both collected by Scott Wing. Collections were made at some USNM localities during multiple years; therefore, the fossils collected from different years have different collector's locality numbers, which were written on the specimens.</p> <p>Field Collection Number: Specimen number assigned during field censuses. Specimens with census numbers were collected and are housed in the Department of Paleobiology, National Museum of Natural History, Smithsonian Institution. Those listed as "C" were tallied on the outcrop.</p> <p>Plant species: Full descriptions and photographs of the plant species and morphotypes are available in <a href="appendix-B.htm">Appendix B</a>.</p> <p>Size: Laminar size, as defined by Webb (1959): lepto = leptophyll, nano = nanophyll, micro = microphyll, noto = notophyll, meso = mesophyll, macro = macrophyll, mega = megaphyll, frag = fragment.</p> <p>DT: Insect damage morphotypes (DTs) observed on each fossil. P1 and P2 were scored for the presence or absence of each damage type (Wilf et al. 2006). For the other seven sites, the number of occurrences of each DT was recorded and is given in parentheses after the DT. For example, 4(2) means that there are two occurrences of DT 4 on the leaf. Piercing and sucking was scored for presence / absence because of the abundance of occurrences of piercing and sucking scars on individual leaves.</p> </blockquote> </blockquote> </blockquote

A new stratigraphic framework and constraints for the position of the Paleocene-Eocene boundary in the rapidly subsiding Hanna Basin, Wyoming

The Paleocene–Eocene strata of the rapidly subsiding Hanna Basin give insights in sedimentation patterns and regional paleogeography during the Laramide orogeny and across the climatic event at the Paleocene–Eocene Thermal Maximum (PETM). Abundant coalbeds and carbonaceous shales of the fluvial, paludal, and lacustrine strata of the Hanna Formation offer a different depositional setting than PETM sections described in the nearby Piceance and Bighorn Basins, and the uniquely high sediment accumulation rates give an expanded and near-complete record across this interval. Stratigraphic sections were measured for an ∼1250 m interval spanning the Paleocene–Eocene boundary across the northeastern syncline of the basin, documenting depositional changes between axial fluvial sandstones, basin margin, paludal, floodplain, and lacustrine deposits. Leaf macrofossils, palynology, mollusks, δ13C isotopes of bulk organic matter, and zircon sample locations were integrated within the stratigraphic framework and refined the position of the PETM. As observed in other basins of the same age, an interval of coarse, amalgamated sandstones occurs as a response to the PETM. Although this pulse of relatively coarser sediment appears related to climate change at the PETM, it must be noted that several very similar sandstone bodies occur with the Hanna Formation. These sandstones occur in regular intervals and have an apparent cyclic pattern; however, age control is not sufficient yet to address the origin of the cyclicity. Signs of increased ponding and lake expansion upward in the section appear to be a response to basin isolation by emerging Laramide uplifts

Hagenia from the early Miocene of Ethiopia: evidence for possible niche evolution?

Fossil pollen believed to be related to extant Hagenia abyssinica were discovered in the early Miocene (21.73 Ma) Mush Valley paleoflora, Ethiopia, Africa. Both the fossil and extant pollen grains of H. abyssinica were examined with combined light microscopy, scanning electron microscopy, and transmission electron microscopy to compare the pollen and establish their relationships. Based on this, the fossil pollen grains were attributed to Hagenia. The presence of Hagenia in the fossil assemblage raises the questions if its habitat has changed over time, and if the plants are/were wind pollinated. To shed light on these questions, the morphology of extant anthers was also studied, revealing specialized hairs inside the anthers, believed to aid in insect pollination. Pollen and anther morphology are discussed in relation to the age and origin of the genus within a molecular dated phylogenetic framework, the establishment of complex topography in East Africa, other evidence regarding pollination modes, and the palynological record. The evidence presented herein, and compiled from the literature, suggests that Hagenia was an insect‐pollinated lowland rainforest element during the early Miocene of the Mush Valley. The current Afromontane habitat and ambophilous (insect and wind) pollination must have evolved in post‐mid‐Miocene times

Appendix D. New insect feeding damage types from the Bighorn Basin floras.

New insect feeding damage types from the Bighorn Basin floras