Adaptive walks on behavioural landscapes and the evolution of optimal behaviour by natural selection

Summary One of the main challenges to the adaptationist programme in general and to the use of optimality models in behavioural and evolutionary ecology in particular is that natural selection need not optimise fitness. This challenge is addressed by considering the evolution of optimal patch choice by natural selection. The behavioural model is based on a state variable approach in which a strategy consists of a sequence denoting the patch to be visited as a function of the organism's state and time. The optimal strategy maximises expected terminal reproduction. The fitnesses of alternative strategies are computed by iteration of the associated equations for fitness; this characterises the adaptive behavioural landscape. There may be enormous numbers of strategies that have near optimal fitnesses. A population model is used to connect frequencies of behavioural types from one generation to the next. Theories on adaptive walks on fitness landscapes are considered in the context of behaviour. The main result is that within the context of optimality arguments at selective equilibrium, sub-optimal behaviours can persist. General implications for research in behavioural ecology, including tests of behavioural theories, are discussed.     

Evolutionary Analysis of Mammalian Enamelin,The Largest Enamel Protein,Supports a Crucial Role for the 32-kDa Peptide and Reveals Selective Adaptation in Rodents and Primates

Enamelin (ENAM) plays an important role in the mineralization of the forming enamel matrix. We have performed an evolutionary analysis of mammalian ENAM to identify highly conserved residues or regions that could have important function (selective pressure), to predict mutations that could be associated with amelogenesis imperfecta in humans, and to identify possible adaptive evolution of ENAM during 200 million years ago of mammalian evolution. In order to fulfil these objectives, we obtained 36-ENAM sequences that are representative of the mammalian lineages. Our results show a remarkably high conservation pattern in the region of the 32-kDa fragment of ENAM, especially its phosphorylation, glycosylation, and proteolytic sites. In primates and rodents we also identified several sites under positive selection, which could indicate recent evolutionary changes in ENAM function. Furthermore, the analysis of the unusual signal peptide provided new insights on the possible regulation of ENAM secretion, a hypothesis that should be tested in the near future. Taken together, these findings improve our understanding of ENAM evolution and provide new information that would be useful for further investigation of ENAM function as well as for the validation of mutations leading to amelogenesis imperfecta.     

Presence of the dinoflagellates Ceratium dens, C. fusus and C. furca (Gonyaulacales: Ceratiaceae) in Golfo de Nicoya, Costa Rica

Harmful Algae Blooms (HAB) are a frequent phenomenon in the Gulf of Nicoya, Costa Rica, as in other parts of the world. The morphology and physiology of these microalgae are important because HAB species have adaptive characteristics. The production of high concentrations of paralytic toxins by Ceratium dinoflagellates has only been documented at the experimental level. However, this genus has been associated with the mortality of aquatic organisms, including oyster and shrimp larva, and fish, and with decreased water quality. Recently, fishermen reported massive mortality of encaged fish near Tortuga Island (Gulf of Nicoya). Samples were taken from an algal bloom that had produced an orange coloration and had a strong foul-smelling odor. Ultrastructural details were examined with scanning electron microscopy. The dinoflagellates Ceratium dens, C. furca and C. fusus were found in samples taken at the surface. The cell count revealed four million cells of this genus per liter. The morphological variability of these species is high; therefore electron microscopy is an useful tool in the ultrastructural study of these organisms. This is the first time that three Ceratium species are reported concurrently producing harmful blooms in Costa Rica.     

Mortality and displaced mortality during heat waves in the Czech Republic

The aims of this study were to assess impacts of hot summer periods on mortality in the Czech Republic and to quantify the size of the short-term displacement effect which resulted in lower than expected mortality after heat waves. The analysis covered the period 1982–2000 when several extraordinarily hot summers occurred in central Europe. Daily total all-cause mortality and mortality due to cardiovascular diseases (CVD) in the entire population of the Czech Republic (approximately 10 million inhabitants) were examined. The daily death counts were standardized to account for the long-term decline in mortality and the seasonal and weekly cycles. Heat-related mortality is better expressed if 1-day lag after temperature is considered compared to the unlagged relationship. With the 1-day lag, both excess total mortality and excess CVD mortality were positive during all 17 heat waves, and in 14 (12) heat waves the increase in total (CVD) mortality was statistically significant (P=0.05). The mean relative rise in total mortality during heat waves was 13%. The response was greater in females than males and similar regardless of whether total or CVD mortality was used. The largest relative increases, exceeding 20% in both total and CVD mortality, were associated with heat waves which occurred in early summer (the first half of July 1984 and June 1994). The mortality displacement effect played an important role since mortality tended to be lower than expected after hot periods. The mean net mortality change due to heat waves was estimated to be about a 1% increase in the number of deaths. The large relative increases during some heat waves were particularly noteworthy since the study (in contrast to most analyses of the heat stress/mortality relationship) was not restricted to an urban area and/or an elderly population.     

On the adaptive significance of energetic efficiency

Models of energetic efficiency have been widely used by ecological anthropologists to study human subsistence patterns. This paper explicitly tests an hypothesis posed by Smith (1979) about energy utilization in the highland community of Nunoa, Peru. Smith's hypothesis is largely confirmed, as greater energy availability is associated with increased caloric consumption and improved measures of health and well-being among the wealthier sectors of this population. However, an energetics model does not provide a full understanding of the behavior and biology of this population. Interacting social/economic and environmental forces impose different constraints on different sectors of this population. These differences are in turn reflected in variation in adaptive strategies and in biological well-being. Future work in human ecology will benefit from (1) attention to the interaction of ecological and socio-economic forces, (2) greater appreciation of intra-populational variation in adaptive strategies, and (3) explicit linking of variation in adaptive strategies to differences in human biological parameters.     

Chronic obstructive pulmonary disease (COPD): Evaluation from clinical,immunological and bacterial pathogenesis perspectives

Chronic obstructive pulmonary disease (COPD), a disease manifested by significantly impaired airflow, afflicts ～14.2 million cases in the United States alone with an estimated 63 million people world-wide. Although there are a number of causes, the predominant cause is excessive tobacco smoke. In fact, in China, there have been estimates of 315,000,000 people that smoke. Other less frequent causes are associated with indirect cigarette smoke, air pollutants, biomass fuels, and genetic mutations. COPD is often associated with heart disease, lung cancer, osteoporosis and conditions can worsen in patients with sudden falls. COPD also affects both innate and adaptive immune processes. Cigarette smoke increases the expression of matrix metalloproteases and proinflammatory chemokines and increases lung titers of natural killer cells and neutrophils. Yet, neutrophil reactive oxygen species (ROS) mediated by the phagocytic respiratory burst and phagocytosis is impaired by nicotine. In contrast to innate immunity in COPD, dendritic cells represent leukocytes recruited to the lung that link the innate immune responses to adaptive immune responses by activating naïve T cells through antigen presentation. The autoimmune process that is also a significant part of inflammation associated with COPD. Moreover, coupled with restricted FEV1 values, are the prevalence of patients with single or multiple infections by bacteria, viruses and fungi. Finally, we focus on one of the more problematic infectious agents, the Gram-negative opportunistic pathogenic bacterium, Pseudomonas aeruginosa. Specifically, we delve into the development of highly problematic biofilm infections that are highly refractory to conventional antibiotic therapies in COPD. We offer a non-conventional, biocidal treatment that may be effective for COPD airway infections as well as with combinations of current antibiotic regimens for more effective treatment outcomes and relief for patients with COPD.     

Crawling to Collapse: Ecologically Unsound Ornamental Invertebrate Fisheries

Background

Fishery management has historically been an inexact and reactionary discipline, often taking action only after a critical stock suffers overfishing or collapse. The invertebrate ornamental fishery in the State of Florida, with increasing catches over a more diverse array of species, is poised for collapse. Current management is static and the lack of an adaptive strategy will not allow for adequate responses associated with managing this multi-species fishery. The last decade has seen aquarium hobbyists shift their display preference from fish-only tanks to miniature reef ecosystems that include many invertebrate species, creating increased demand without proper oversight. The once small ornamental fishery has become an invertebrate-dominated major industry supplying five continents.

Methodology/Principal Findings

Here, we analyzed the Florida Marine Life Fishery (FLML) landing data from 1994 to 2007 for all invertebrate species. The data were organized to reflect both ecosystem purpose (in the wild) and ecosystem services (commodities) for each reported species to address the following question: Are ornamental invertebrates being exploited for their fundamental ecosystem services and economic value at the expense of reef resilience? We found that 9 million individuals were collected in 2007, 6 million of which were grazers.

Conclusions/Significance

The number of grazers now exceeds, by two-fold, the number of specimens collected for curio and ornamental purposes altogether, representing a major categorical shift. In general, landings have increased 10-fold since 1994, though the number of licenses has been dramatically reduced. Thus, despite current management strategies, the FLML Fishery appears to be crawling to collapse.     

The amphioxus genome provides unique insight into the evolution of immunity

Immune systems evolve as essential strategies to maintain homeostasis with the environment, prevent microbial assault and recycle damaged host tissues. The immune system is composed of two components, innate and adaptive immunity. The former is common to all animals while the latter consists of a vertebrate-specific system that relies on somatically derived lymphocytes and is associated with near limitless genetic diversity as well as long-term memory. Deuterostome invertebrates provide a view of immune repertoires in phyla that immediately predate the origins of vertebrates. Genomic studies in amphioxus, a cephalochordate, have revealed homologs of genes encoding most innate immune receptors found in vertebrates; however, many of the gene families have undergone dramatic expansions, greatly increasing the innate immune repertoire. In addition, domain-swapping accounts for the innovation of new predicted pathways of receptor function. In both amphioxus and Ciona, a urochordate, the VCBPs (variable region containing chitin-binding proteins), which consist of immunoglobulin V (variable) and chitin binding domains, mediate recognition through the V domains. The V domains of VCBPs in amphioxus exhibit high levels of allelic complexity that presumably relate to functional specificity. Various features of the amphioxus immune repertoire reflect novel selective pressures, which likely have resulted in innovative strategies. Functional genomic studies underscore the value of amphioxus as a model for studying innate immunity and may help reveal how unique relationships between innate immune receptors and both pathogens and symbionts factored in the evolution of adaptive immune systems.     

Developmental stability and adaptive radiation in the Spalax ehrenbergi superspecies in the Near-East

Chromosomal species of the mole rat, Spalax ehrenbergi, in Israel have been shown to display distinct adaptive strategies to increasing aridity. This adaptive radiation appeared to be associated with an increase in allozymic heterozygosity. In the present study, the developmental stability (DS) estimated by fluctuating asymmetry (FA) of dental traits was used to assess the suitability of habitat and the efficiency of adaptation to local environmental conditions among populations and chromosomal species. Although FA levels were highly heterogeneous among populations, they were not found to differ between species. DS of populations appeared, however, to be impaired at higher altitudes and in indurate soils. Since these environmental features were largely covariant, the effect of each one could not be precisely determined. Interestingly, while aridity is considered as the major selective force acting on populations southwards, DS was not altered under arid conditions, suggesting that mole rat populations were adapted to their local conditions of aridity. However, the cline of aridity is matched to several environmental and genetic clines among which are the increasing heterozygosity and recombination rate among species southwards. In studies of natural populations, the potential complementary effects of environmental and genetics on DS have to be considered and hamper the interpretation of habitat suitability expressed by DS in terms of adaptive strategies.     

Follicle selection in cattle: follicle deviation and codominance within sequential waves

Follicle deviation during bovine follicular waves is characterized by continued growth of a developing dominant follicle and reduction or cessation of growth of subordinate follicles. Characteristics of follicle deviation for waves with a single dominant follicle were compared between wave 1 (begins near ovulation; n = 15) and wave 2 (n = 15). Follicles were defined as F1 (largest), F2, and F3, according to maximum diameter. No mean differences were found between waves for follicle diameters at expected deviation (F1, > or =8.5 mm; Hour 0) or observed deviation or in the interval from follicle emergence at 4.0 mm to deviation. For both waves, circulating FSH continued to decrease (P < 0.05) after Hour 0, estradiol began to increase (P < 0.05) at Hour 0, and immunoreactive inhibin began to decrease (P < 0.05) before Hour 0. A transient elevation in circulating LH reached maximum concentration at Hour 0 (P < 0.01) in both waves and was more prominent (P < 0.0001) for wave 1. Waves with codominant follicles (both follicles >10 mm) were more common (P < 0.02) for wave 1 (35%) than for wave 2 (4%). Codominants (n = 6) were associated with more (P < 0.05) follicles > or=4 mm and a greater concentration (P < 0.04) of circulating estradiol at Hours -48 to -8 than were single dominant follicles (n = 15). A mean transient increase in FSH and LH occurred in the codominant group at Hour -24 and may have interfered with deviation of F2. In codominant waves, deviation of F3 occurred near Hour 0 (F1, approximately 8.5 mm). A second deviation involving F2 occurred in four of six waves a mean of 50 h after the F3 deviation and may have resulted from a greater suppression (P < 0.05) of FSH in the codominant group after Hour 0. In conclusion, follicle or hormone differences were similar for waves 1 and 2, indicating that the deviation mechanisms were the same for both waves. Waves that developed codominant follicles differed in hormone as well as follicle dynamics.     

禁牧政策下宁夏盐池县农户适应策略及其影响因素

禁牧政策下农户的适应策略是农户为了应对外界干预而做出的各种适应性改变,生计变化是其中最重要的部分。通过实地调查获得研究数据,对比分析禁牧初期和禁牧10a农户生计模式、养殖及种植方面的变化,并以农户的生计资本作为自变量,运用有序多分类和二项的Logistic回归模型分析农户适应策略(农户生计多样性、养殖规模及养殖方式)变化的影响因素。研究得出:1与禁牧初期相比,当前农户的适应策略主要表现为农户生计模式具有初步非农化倾向,生计多样性增加,大部分农户养殖规模减小或不变,农户生产结构有所调整,粮食作物种植面积增加,而经济作物种植面积减小,单只羊的养殖成本增加。2农户生计资本水平对其适应策略具有重要影响,农户生计多样性变化的主要影响因素有人力资本、金融资本和社会资本;影响农户养殖规模变化的主要有自然资本、物质资本、金融资本和社会资本,而影响农户养殖模式选择的主要是物质资本和金融资本因素。     

Follicular and FSH dynamics in ewes with a history of high and low ovulation rates

Daily transrectal ultrasound scanning and twice-daily blood sampling were used to monitor the temporal relationships between FSH concentrations and follicle development during complete interovulatory intervals for ewes in which the ovulation rate in each of the 2 previous years was high or low (> or = 3 and < or = 2 ovulations, respectively). Follicles that reached > or = 5 mm were used to define a follicular wave and were tracked retrospectively to 3 mm (emergence). The hypothesis that FSH surges (identified with a computer program) and follicular waves (retrospectively determined based on ultrasound scanning) are temporally associated was supported in both groups by the emergence of an anovulatory or ovulatory follicular wave near the peak of an FSH surge. Further support for the hypothesis was a significant increase in FSH concentrations before and a significant decrease after follicular-wave emergence in both groups independent of the identification of FSH surges. Ewes with a history of high ovulation rates had smaller follicles (anovulatory and ovulatory) and more ovulations, but the 2 groups were similar in the number of ovulatory follicular waves and associated FSH surges, number and characteristics of the FSH surges, and mean FSH concentrations per interovulatory interval. Surges of FSH were periodic (every 3 or 4 d) regardless of the ovulation-rate group or follicle response. In ewes with a low ovulation rate, the nonovulatory FSH surges were most frequently associated with emergence of detected anovulatory follicular waves. In ewes with a high ovulation rate, more FSH surges were not associated with a detected follicular wave, as defined, presumably because the largest follicle did not reach 5 mm. The results indicated that the factors resulting in a high ovulation rate were not exerted through circulatory patterns or concentrations of FSH but involved a shorter growth phase and smaller maximal diameter of follicles.     

The oldest South American tuco-tuco (late Pliocene,northwestern Argentina) and the boundaries of the genus Ctenomys (Rodentia,Ctenomyidae)

A new species of Ctenomyidae from the late Pliocene of Uquía Formation (northwestern Argentina) is described. The new remains consist of a fragmentary rostrum, and a left mandible with partial lower dentition. Its phylogenetic affinity and morphological specializations for tooth-digging support its assignation to the South American rodent genus Ctenomys. In this context, we highlight the importance of unique morphological specializations for the delimitation of genera within an intrafamilial clade in which similar adaptive strategies could have evolved more than once. The new materials are the oldest fossils for the genus (ca. 3.5 Ma), and their finding in the central Andes agrees with previous hypotheses about the possible area of origin of Ctenomys. They precede by about one million years the presence of Ctenomys chapalmalensis in the Pliocene of the Pampean region of central Argentina, the oldest record previously known for the genus. Nevertheless, the new species does not contribute key information about ancestral character states for the genus beyond those already known through C. chapalmalensis. The phylogenetic, adaptive and even chronological information supplied by these new materials would be linked to the differentiation of the genus rather than to its origin.     

Cholinergic microstimulation of the peribrachial nucleus in the cat. I. Immediate and prolonged increases in ponto-geniculo-occipital waves.

The cholinergic agonist carbachol was injected into the pontine Pb area where PGO bursting cells have been recorded. When microinjections were localized to the ventrolateral aspect of the caudal Pb nucleus near aggregates of ChAT immunolabeled cholinergic neurons, carbachol produced an immediate onset of state-independent PGO waves in the ipsilateral LGB. These state-independent PGO waves persisted for 3-4 days. After the first 24 hrs PGO wave activity increasingly became associated with REM sleep and with REM transitional SP sleep as both of these PGO-related states increased in amount to 3-4 times baseline levels. The increase in amount of PGO-related states peaked on days 2-4 following one carbachol injection and persisted for 10-12 days. These results suggest a two stage process: stage one, PGO enhancement, is the direct consequence of the membrane activation of cholinoceptive PGO burst neurons by carbachol; stage two, REM enhancement, is the consequence of metabolic activation of endogenous cholinergic neurons. This experimental preparation is a useful model for the study of the electrophysiology and functional significance of PGO wave and REM sleep generation.     

Evaluation of the plan for surveillance and controlling of the effects of heat waves in Madrid

This paper presents evaluation of a plan for surveillance of and controlling the effects of heat-related mortality (PSCEHW), implemented in Madrid in 2004 through a time series analysis conducted with ARIMA modeling. From the public health point of view, prevention plans should be implemented as adaptive measures to heat waves. In 2003, the impact attributable to the heat wave was an increase in mortality per °C of 22.39 %. All heat waves since 2003 have been of lower intensity, and yet, in 2005 there was a heat wave of lower intensity that had a greater impact, i.e. an increase in mortality per °C of 45.71 %. With the methodology used here, we cannot say whether implementation of PSCEHW has resulted in a decrease of mortality attributable to high temperatures in the city of Madrid.     

Trait diversity on the phylogeny of cerrado woody species

During the Neogene, the Brazilian cerrado became established as a large‐scale vegetation type. Cerrado lineages started to diversify less than 10 million years ago, coinciding with the rise to dominance of flammable C₄ grasses and the expansion of the savanna biome. Cerrado lineages are strongly associated with adaptations to fire and have sister groups in fire‐free nearby forests, implying that the cerrado formed in situ via adaptive shifts to resist fire. By including phylogeny into the analysis of biological traits, we investigated trait diversity of cerrado woody species in a phylogenetic context, sampling a cerrado site in central Brazil. Decomposing trait diversity along the nodes of a phylogenetic tree of cerrado woody species, we found that the rate of trait diversification was higher in the past, coinciding with the major species diversification of angiosperms in mid‐Cretaceous, long before the cerrado originated. Some more recent adaptive shifts to resist fire, however, must have occurred during the origin and expansion of the cerrado woody flora. Analysing values of each trait separately at the tips of the phylogenetic tree, we found that most trait values were randomly distributed, probably because we analysed only species that had already been filtered by drought, fire, and soil. Analysing values of all traits simultaneously at the tips, we found close to root events and broad, macro‐evolutionary patterns, called ‘global structures’, opposing some lineages, especially Fabaceae and Myrtaceae, with different ecological strategies. Fabaceae presented compound, large, tender leaves, with high nitrogen content due to symbiosis with nitrogen‐fixing bacteria, and Myrtaceae presented simple, small, tough leaves, with low nitrogen and high potassium content. We also found relatively recent events that induced divergence of the evolutionary strategies close to the tips, called ‘local structures’, involving more recent changes in most lineages.     

Dynamics of nutrient uptake strategies: lessons from the tortoise and the hare

Many autotrophs vary their allocation to nutrient uptake in response to environmental cues, yet the dynamics of this plasticity are largely unknown. Plasticity dynamics affect the extent of single versus multiple nutrient limitation and thus have implications for plant ecology and biogeochemical cycling. Here we use a model of two essential nutrients cycling through autotrophs and the environment to determine conditions under which different plastic or fixed nutrient uptake strategies are adaptive. Our model includes environment-independent costs of being plastic, environment-dependent costs proportional to the rate of plastic change, and costs of being mismatched to the environment, the last of which is experienced by both fixed and plastic types. In equilibrium environments, environment-independent costs of being plastic select for tortoise strategies—fixed or less plastic types—provided that they are sufficiently close to co-limitation. At intermediate levels of environmental fluctuation forced by periodic nutrient inputs, more hare-like plastic strategies prevail because they remain near co-limitation. However, the fastest is not necessarily the best. The most adaptive strategy is an intermediate level of plasticity that keeps pace with environmental fluctuations, but is not faster. At high levels of environmental fluctuation, the environment-dependent cost of changing rapidly to keep pace with the environment becomes prohibitive and tortoise strategies again dominate. The existence and location of these thresholds depend on plasticity costs and rate, which are largely unknown empirically. These results suggest that the expectations for single nutrient limitation versus co-limitation and therefore biogeochemical cycling and autotroph community dynamics depend on environmental heterogeneity and plasticity costs.     

SELDI-TOF-MS ProteinChip array profiling of T-cell clones propagated in long-term culture identifies human profilin-1 as a potential bio-marker of immunosenescence

Background  

The adaptive immune response requires waves of T-cell clonal expansion on contact with pathogen and elimination after clearance of the source of antigen. However, lifelong persistent infections with common viruses cause chronic antigenic stimulation which takes its toll on adaptive immunity in late life. Chronic antigenic stress results in deregulation of the T-cell response and accumulation of anergic cells. Longitudinal studies of the elderly show that this impacts on survival. Identifying the nature of the defects in chronically-stimulated T-cells and protein bio-markers of these dysfunctional cells would help to understand age-associated compromised T-cell function (immunosenescence) and facilitate the development of targeted intervention strategies.     

An Enhanced Adaptive Management Approach for Remediation of Legacy Mercury in the South River

Uncertainties about future conditions and the effects of chosen actions, as well as increasing resource scarcity, have been driving forces in the utilization of adaptive management strategies. However, many applications of adaptive management have been criticized for a number of shortcomings, including a limited ability to learn from actions and a lack of consideration of stakeholder objectives. To address these criticisms, we supplement existing adaptive management approaches with a decision-analytical approach that first informs the initial selection of management alternatives and then allows for periodic re-evaluation or phased implementation of management alternatives based on monitoring information and incorporation of stakeholder values. We describe the application of this enhanced adaptive management (EAM) framework to compare remedial alternatives for mercury in the South River, based on an understanding of the loading and behavior of mercury in the South River near Waynesboro, VA. The outcomes show that the ranking of remedial alternatives is influenced by uncertainty in the mercury loading model, by the relative importance placed on different criteria, and by cost estimates. The process itself demonstrates that a decision model can link project performance criteria, decision-maker preferences, environmental models, and short- and long-term monitoring information with management choices to help shape a remediation approach that provides useful information for adaptive, incremental implementation.     

Conservation management in the face of climatic uncertainty – the roles of flexibility and robustness

Climate change is uncertain and has uncertain effects on the suitabilities of species habitats. Conservation strategies have to take this uncertainty into account. Two concepts for addressing uncertainty are, to make strategies adaptive and robust. Using a stylized ecological-economic model in which a decision maker can allocate a conservation budget between two time periods and two regions, I explore how the cost-effective allocation of the budget depends on ecological and economic parameters, including parameters describing the uncertain dynamics of climate change; and under which circumstances adaptive allocation strategies significantly outperform fixed strategies. Even if an adaptive strategy is politically feasible, its optimisation requires some knowledge about the dynamics of the climate change in the form of statistics like mean and variance of climate parameters. If these statistics are estimated wrong then even an adaptive strategy may fail. To explore the risk of such failure I subject the cost-effective strategies derived in the first part of the analysis to a robustness analysis that, among others, identifies those strategies that are relatively prone to wrong expectations of the climate change. Amongst others, the analysis reveals that flexibility pays only if there is uncertainty in the relative performances of different strategies; and depending on whether substitution between the benefits of the two time periods is allowed or not, the most robust strategy is to concentrate conservation expenses to the first period or to allocate the budget evenly amongst the two time periods, respectively.