Is Evolution of Blind Mole Rats Determined by Climate Oscillations?

The concept of climate variability facilitating adaptive radiation supported by the ‘‘Court Jester’’ hypothesis is disputed by the ‘‘Red Queen’’ one, but the prevalence of one or the other might be scale-dependent. We report on a detailed, comprehensive phylo-geographic study on the ,4 kb mtDNA sequence in underground blind mole rats of the family Spalacidae (or subfamily Spalacinae) from the East Mediterranean steppes. Our study aimed at testing the presence of periodicities in branching patterns on a constructed phylogenetic tree and at searching for congruence between branching events, tectonic history and paleoclimates. In contrast to the strong support for the majority of the branching events on the tree, the absence of support in a few instances indicates that network-like evolution could exist in spalacids. In our tree, robust support was given, in concordance with paleontological data, for the separation of spalacids from muroid rodents during the first half of the Miocene when open, grass-dominated habitats were established. Marine barriers formed between Anatolia and the Balkans could have facilitated the separation of the lineage ‘‘Spalax’’ from the lineage ‘‘Nannospalax’’ and of the clade ‘‘leucodon’’ from the clade ‘‘xanthodon’’. The separation of the clade ‘‘ehrenbergi’’ occurred during the late stages of the tectonically induced uplift of the Anatolian high plateaus and mountains, whereas the separation of the clade ‘‘vasvarii’’ took place when the rapidly uplifting Taurus mountain range prevented the Mediterranean rainfalls from reaching the Central Anatolian Plateau. The separation of Spalax antiquus and S. graecus occurred when the southeastern Carpathians were uplifted. Despite the role played by tectonic events, branching events that show periodicity corresponding to 400-kyr and 100-kyr eccentricity bands illuminate the important role of orbital fluctuations on adaptive radiation in spalacids. At the given scale, our results supports the ‘‘Court Jester’’ hypothesis over the ‘‘Red Queen’’ one

Palaeocene–Eocene miospores from the Chicxulub impact crater, Mexico. Part 1:spores and gymnosperm pollen

In the summer of 2016, the International Ocean Discovery Program (IODP) Expedition 364 coredthrough the post-impact strata of the end-Cretaceous Chicxulub impact crater, Mexico. Core sampleswere collected from the post-impact successions for terrestrial palynological analysis, yielding a rareDanian to Ypresian high-resolution palynological assemblage. This record constitutes one of the firstPalaeocene and Ypresian palynological assemblages from Central America or Mexico, representing amore coastal lowland palaeoenvironment than previous studies from mainland Mexico. Although theabundance of pollen and spores is very low in the Palaeocene carbonates, abundance increases in themore organic-rich shale layers representing the Palaeocene–Eocene Thermal Maximum (PETM) andlater Ypresian. The spores and gymnosperm pollen identified from IODP 364, although rare comparedto the angiosperm pollen, are a diverse mix of cosmopolitan taxa, as well as some characteristic of fossilCentral American assemblages (e.g. Selaginellaceae), and others previously identified from thePaleogene northern Gulf of Mexico coastal plain. The assemblage generally indicates the presence ofnearby moist to seasonally dry lowland tropical forest, with some taxa suggestive of higher elevationforests. Ephedroid pollen grains may be indicative of the presence of more arid conditions

Paleocene–Eocene palynomorphs from the Chicxulub impact crater, Mexico.Part 2: angiosperm pollen

At the end of the Cretaceous Period, an asteroid collided with the Earth and formed the Chicxulub impact structure on the Yucatan Platform. International Ocean Discovery Program (IODP) Expedition 364 drilled into the peak ring of the Chicxulub impact crater. The post-impact section of the core was sampled for terrestrial palynological analysis, yielding a high-resolution record ranging from the early Paleocene to the earliest Eocene (Ypresian), including a black shale deposited during the Paleocene–Eocene Thermal Maximum (PETM). The IODP 364 core provides the first record of floral recovery following the K–Pg mass extinction from inside the Chicxulub impact crater. The systematic taxonomy of the angiosperm pollen provided here follows a separate publication describing the systematic paleontology of the plant spores and gymnosperm pollen from the IODP 364 core (Smith et al. 2019). The Paleocene section of the core is nearly barren, but with unusually high relative abundances of the angiosperm pollen Chenopodipollis sp. A (comparable to the Amaranthaceae), possibly indicating an estuarine pollen source. Pollen recovery is higher in the PETM section, and variable but generally increasing in the later Ypresian section, with excellent preservation in several samples. Estimated absolute ages of several potentially useful regional biostratigraphic events are provided. One new genus (Scabrastephanoporites) and five new species (Brosipollis reticulatus, Echimonocolpites chicxulubensis, Psilastephanocolporites hammenii, Scabrastephanoporites variabilis, and Striatopollisgrahamii) are formally described