Book Reviews

Obra ressenyada: W. WEITSCHAT and W. WICHARD, Atlas of Plants and Animals in Baltic Amber. Munich: Verlag Dr. Friedrich Pfeil, 2002

The Four Phases of Plant-Arthropod Associations in Deep Time

Vascular-plant hosts, their arthropod herbivores, and associated functional feeding groups are distributed spatiotemporally into four major herbivore expansions during the past 420 m.y. They are: (1) a Late Silurian to Late Devonian (60 m.y.) phase of myriapod and apterygote, hexapod (perhaps pterygote) herbivores on several clades of primitive vascular-plant hosts and a prototaxalean fungus; (2) a Late Mississippian to end-Permian (85 m.y.) phase of mites and apterygote and basal pterygote herbivores on pteridophyte and basal gymnospermous plant hosts; (3) a Middle Triassic to Recent (245 m.y.) phase of mites, orthopteroids (in the broadest sense) and hemipteroid and basal holometabolan herbivores on pteridophyte and gymnospermous plant hosts; and (4) a mid Early Cretaceous to Recent (115 m.y.) phase of modern-aspect orthopteroids and derived hemipteroid and holometabolous herbivores on angiospermous plant hosts. These host-plant and herbivore associations are mediated by seven functional feeding groups: a) external foliage feeding, b) piercing-and-sucking, c) boring (Phase 1 origins); d) galling, e) seed predation, f) nonfeeding oviposition (Phase 2 origins); and leaf mining (early Phase 3 origin). Within about 20 m.y. of each herbivore expansion, there is a biota that expresses the nearly full spectrum of later plant-arthropod associations. These four associational phases may be linked to the paleoclimatologic variables of greenhouse/icehouse cycles and atmospheric O2 and CO2 levels by uncertain causes, although some relationship probably is present. The 7 functional feeding groups persist through most of the sampled interval but harbor host-plants and arthropod herbivores that are spatiotemporally ephemeral. Poor understanding of associations in Phases 1 to 3 is attributed to disproportionate focus on the angiosperm and holometabolan insect associations of Phase 4

A \u3cem\u3eDendroctonus\u3c/em\u3e Bark Engraving (Coleoptera: Scolytidae) From A Middle Eocene \u3cem\u3eLarix\u3c/em\u3e (Coniferales: Pinaceae): Early Or Delayed Colonization?

An engraving made by a scolytid bark beetle, assigned to the genus Dendroctonus of the tribe Tomicini, has been identified on a mummified, middle Eocene (45 Ma) specimen of Larix altoborealis wood from the Canadian High Arctic. Larix altoborealis is the earliest known species of Larix, a distinctive lineage of pinaceous conifers that is taxonomically identifiable by the middle Eocene and achieved a broad continental distribution in northern North America and Eurasia during the late Cenozoic. Dendroctonus currently consists of three highly host-specific lineages that have pinaceous hosts: a basal monospecific clade on Pinoideae (Pinus) and two sister clades that consist of a speciose clade associated exclusively with Pinoideae and six species that breed overwhelmingly in Piceoideae (Picea) and Laricoideae (Pseudotsuga and Larix). The middle Eocene engraving in L. altoborealis represents an early member of Dendroctonus that is ancestral to other congeneric species that colonized a short-bracted species of Larix. This fossil occurrence, buttressed by recent data on the phylogeny of Pinaceae subfamilies and Dendroctonus species, indicates that there was phylogenetically congruent colonization by these bark-beetle lineages of a Pinoideae + (Piceoideae + Laricoideae) host-plant sequence. Based on all available evidence, an hypothesis of a geochronologically early invasion during the Early Cretaceous is supported over an alternative view of late Cenozoic cladogenesis by bark beetles onto the Pinaceae. These data also suggest that host-plant chemistry may be an effective species barrier to colonization by some bark-beetle taxa over geologically long time scales

Life habits, hox genes, and affinities of a 311 million-year-old holometabolan larva

Background: Holometabolous insects are the most diverse, speciose and ubiquitous group of multicellular organisms in terrestrial and freshwater ecosystems. The enormous evolutionary and ecological success of Holometabola has been attributed to their unique postembryonic life phases in which nonreproductive and wingless larvae differ significantly in morphology and life habits from their reproductive and mostly winged adults, separated by a resting stage, the pupa. Little is known of the evolutionary developmental mechanisms that produced the holometabolous larval condition and their Paleozoic origin based on fossils and phylogeny. Results: We provide a detailed anatomic description of a 311 million-year-old specimen, the oldest known holometabolous larva, from the Mazon Creek deposits of Illinois, U.S.A. The head is ovoidal, downwardly oriented, broadly attached to the anterior thorax, and bears possible simple eyes and antennae with insertions encircled by molting sutures;other sutures are present but often indistinct. Mouthparts are generalized, consisting of five recognizable segments: a clypeo-labral complex, mandibles, possible hypopharynx, a maxilla bearing indistinct palp-like appendages, and labium. Distinctive mandibles are robust, triangular, and dicondylic. The thorax is delineated into three, nonoverlapping regions of distinctive surface texture, each with legs of seven elements, the terminal-most bearing paired claws. The abdomen has ten segments deployed in register with overlapping tergites;the penultimate segment bears a paired, cercus-like structure. The anterior eight segments bear clawless leglets more diminutive than the thoracic legs in length and cross-sectional diameter, and inserted more ventrolaterally than ventrally on the abdominal sidewall. Conclusions: Srokalarva berthei occurred in an evolutionary developmental context likely responsible for the early macroevolutionary success of holometabolous insects. Srokalarva berthei bore head and prothoracic structures, leglet series on successive abdominal segments - in addition to comparable features on a second taxon eight million-years-younger - that indicates Hox-gene regulation of segmental and appendage patterning among earliest Holometabola. Srokalarva berthei body features suggest a caterpillar-like body plan and head structures indicating herbivory consistent with known, contemporaneous insect feeding damage on seed plants. Taxonomic resolution places Srokalarva berthei as an extinct lineage, apparently possessing features closer to neuropteroid than other holometabolous lineages

The fossil record and taphonomy of butterflies and moths (Insecta, Lepidoptera): implications for evolutionary diversity and divergence-time estimates

It is conventionally accepted that the lepidopteran fossil record is significantly incomplete when compared to the fossil records of other, very diverse, extant insect orders. Such an assumption, however, has been based on cumulative diversity data rather than using alternative statistical approaches from actual specimen counts. We reviewed documented specimens of the lepidopteran fossil record, currently consisting of 4,593 known specimens that are comprised of 4,262 body fossils and 331 trace fossils. The temporal distribution of the lepidopteran fossil record shows significant bias towards the late Paleocene to middle Eocene time interval. Lepidopteran fossils also record major shifts in preservational style and number of represented localities at the Mesozoic stage and Cenozoic epoch level of temporal resolution. Only 985 of the total known fossil specimens (21.4%) were assigned to 23 of the 40 extant lepidopteran superfamilies. Absolute numbers and proportions of preservation types for identified fossils varied significantly across superfamilies. The secular increase of lepidopteran family-level diversity through geologic time significantly deviates from the general pattern of other hyperdiverse, ordinal-level lineages. Our statistical analyses of the lepidopteran fossil record show extreme biases in preservation type, age, and taxonomic composition. We highlight the scarcity of identified lepidopteran fossils and provide a correspondence between the latest lepidopteran divergence-time estimates and relevant fossil occurrences at the superfamily level. These findings provide caution in interpreting the lepidopteran fossil record through the modeling of evolutionary diversification and in determination of divergence time estimates.https://doi.org/10.1186/s12862-015-0290-

Insect herbivore and fungal communities on Agathis (Araucariaceae) from the latest Cretaceous to Recent

Agathis (Araucariaceae) is a genus of broadleaved conifers that today inhabits lowland to upper montane rainforests of Australasia and Southeast Asia. A previous report showed that the earliest known fossils of the genus, from the early Paleogene and possibly latest Cretaceous of Patagonian Argentina, host diverse assemblages of insect and fungal associations, including distinctive leaf mines. Here, we provide complete documentation of the fossilized Agathis herbivore communities from Cretaceous to Recent, describing and comparing insect and fungal damage on Agathis across four latest Cretaceous to early Paleogene time slices in Patagonia with that on 15 extant species. Notable fossil associations include various types of external foliage feeding, leaf mines, galls, and a rust fungus. In addition, enigmatic structures, possibly armored scale insect (Diaspididae) covers or galls, occur on Agathis over a 16-million-year period in the early Paleogene. The extant Agathis species, throughout the range of the genus, are associated with a diverse array of mostly undescribed damage similar to the fossils, demonstrating the importance of Agathis as a host of diverse insect herbivores and pathogens and their little-known evolutionary history

Priors and Posteriors in Bayesian Timing of Divergence Analyses : The Age of Butterflies Revisited

The need for robust estimates of times of divergence is essential for downstream analyses, yet assessing this robustness is still rare. We generated a time-calibrated genus-level phylogeny of butterflies (Papilionoidea), including 994 taxa, up to 10 gene fragments and an unprecedented set of 12 fossils and 10 host-plant node calibration points. We compared marginal priors and posterior distributions to assess the relative importance of the former on the latter. This approach revealed a strong influence of the set of priors on the root age but for most calibrated nodes posterior distributions shifted from the marginal prior, indicating significant information in the molecular data set. Using a very conservative approach we estimated an origin of butterflies at 107.6 Ma, approximately equivalent to the latest Early Cretaceous, with a credibility interval ranging from 89.5 Ma (mid Late Cretaceous) to 129.5 Ma (mid Early Cretaceous). In addition, we tested the effects of changing fossil calibration priors, tree prior, different sets of calibrations and different sampling fractions but our estimate remained robust to these alternative assumptions. With 994 genera, this tree provides a comprehensive source of secondary calibrations for studies on butterflies.Peer reviewe

A framework for evaluating the influence of climate, dispersal limitation, and biotic interactions using fossil pollen associations across the late Quaternary

Environmental conditions, dispersal lags, and interactions among species are major factors structuring communities through time and across space. Ecologists have emphasized the importance of biotic interactions in determining local patterns of species association. In contrast, abiotic limits, dispersal limitation, and historical factors have commonly been invoked to explain community structure patterns at larger spatiotemporal scales, such as the appearance of late Pleistocene no-analog communities or latitudinal gradients of species richness in both modern and fossil assemblages. Quantifying the relative influence of these processes on species co-occurrence patterns is not straightforward. We provide a framework for assessing causes of species associations by combining a null-model analysis of co-occurrence with additional analyses of climatic differences and spatial pattern for pairs of pollen taxa that are significantly associated across geographic space. We tested this framework with data on associations among 106 fossil pollen taxa and paleoclimate simulations from eastern North America across the late Quaternary. The number and proportion of significantly associated taxon pairs increased over time, but only 449 of 56 194 taxon pairs were significantly different from random. Within this significant subset of pollen taxa, biotic interactions were rarely the exclusive cause of associations. Instead, climatic or spatial differences among sites were most frequently associated with significant patterns of taxon association. Most taxon pairs that exhibited co-occurrence patterns indicative of biotic interactions at one time did not exhibit significant associations at other times. Evidence for environmental filtering and dispersal limitation was weakest for aggregated pairs between 16 and 11 kyr BP, suggesting enhanced importance of positive species interactions during this interval. The framework can thus be used to identify species associations that may reflect biotic interactions because these associations are not tied to environmental or spatial differences. Furthermore, temporally repeated analyses of spatial associations can reveal whether such associations persist through time